Acid-base dissociable antibiotic-metal complexes are known to be emerging contaminants in the aquatic environments.However,little information is available on the photochemical properties and toxicity of these complex ...Acid-base dissociable antibiotic-metal complexes are known to be emerging contaminants in the aquatic environments.However,little information is available on the photochemical properties and toxicity of these complex forms.This study investigated the spectral properties of three fluoroquinolones(FQs)with and without metal ions Fe(III),Cu(II),and Al(III)in solutions under different pH conditions,as well as evaluated the changes in toxicity due to the complex with thesemetal ions using luminescent bacteria(vibrio fischeri).FQs showed a higher tendency to coordinate metal ions under alkaline conditions compared to neutral and acidic conditions,and the formation of complexes weakened the ultravioletabsorbing ability of FQs.At pH=7.0,Cu(II)quenched the fluorescence intensity of FQs.Moreover,their Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were explored,revealing that the coordination sites of Cu(II)in three FQs were situated in a bidentate manner through the oxygen atom of the deprotonated carboxyl group and cyclic carbonyl oxygen atom.This conclusion was further verified by the theory of molecular surface electrostatic potential.In addition,except for complexes of ciprofloxacin-metals,enhanced toxicity of FQs upon coordination with Fe(III)was observed,while reduced toxicity was found for coordination with Cu(II)and Al(III).These results are important for accurately evaluating the photochemical behavior and risk of these antibiotics in aquatic environments contaminated with metal ions.展开更多
The investigation of reaction kinetics is the key to understanding the nature of reaction processes.However,monitoring fast photochemical reactions by mass spectrometry remains challenging.Herein,we developed an optic...The investigation of reaction kinetics is the key to understanding the nature of reaction processes.However,monitoring fast photochemical reactions by mass spectrometry remains challenging.Herein,we developed an optical focusing inductive electrospray(OF-iESI)mass spectrometry platform for real-time and in-situ photoreaction monitoring.Coaxial irradiation from back of nanoelectrospray emitter with a taper section was utilized,so the emitter could act as optical lens to help achieving much larger optical power density at emitter tip compared to other sections,which allowed for in-situ reaction monitoring of photoreactions.Through theoretical calculations,the highest optical power density region volume was ca.45 nL.We also integrated a controller for the laser source(450 nm),enabling the modulation of pulse duration(>1 ms).This facilitates the study of photochemical reaction kinetics.The in-situ capability of this device was proved by capturing the short-lived photogenerated intermediates during the dehydrogenation of tetrahydroquinoline.This device was further used to investigate the kinetics of triplet energy transfer based Paternò-Büchi reaction.The reaction order has hitherto remained undetermined while the result of OF-iESI suggested it followed pseudo-second-order reaction kinetics.The short-lived donor-acceptor collision complex intermediate was also successfully identified by tandem mass spectrometry.展开更多
Substantial effects of photochemical reaction losses of volatile organic compounds(VOCs)on factor profiles can be investigated by comparing the differences between daytime and nighttime dispersion-normalized VOC data ...Substantial effects of photochemical reaction losses of volatile organic compounds(VOCs)on factor profiles can be investigated by comparing the differences between daytime and nighttime dispersion-normalized VOC data resolved profiles.Hourly speciated VOC data measured in Shijiazhuang,China from May to September 2021 were used to conduct study.The mean VOC concentration in the daytime and at nighttime were 32.8 and 36.0 ppbv,respectively.Alkanes and aromatics concentrations in the daytime(12.9 and 3.08 ppbv)were lower than nighttime(15.5 and 3.63 ppbv),whereas that of alkenes showed the opposite tendency.The concentration differences between daytime and nighttime for alkynes and halogenated hydrocarbonswere uniformly small.The reactivities of the dominant species in factor profiles for gasoline emissions,natural gas and diesel vehicles,and liquefied petroleum gas were relatively low and their profiles were less affected by photochemical losses.Photochemical losses produced a substantial impact on the profiles of solvent use,petrochemical industry emissions,combustion sources,and biogenic emissions where the dominant species in these factor profiles had high reactivities.Although the profile of biogenic emissions was substantially affected by photochemical loss of isoprene,the low emissions at nighttime also had an important impact on its profile.Chemical losses of highly active VOC species substantially reduced their concentrations in apportioned factor profiles.This study results were consistent with the analytical results obtained through initial concentration estimation,suggesting that the initial concentration estimation could be the most effective currently availablemethod for the source analyses of active VOCs although with uncertainty.展开更多
Light exposure can accelerate phase transformation of Schwertmannite(Sch)coexisting with lowmolecular-weight organic acids(LMWOAs),affecting the cycling of Fe in acid mine drainage(AMD).However,it is still unclear how...Light exposure can accelerate phase transformation of Schwertmannite(Sch)coexisting with lowmolecular-weight organic acids(LMWOAs),affecting the cycling of Fe in acid mine drainage(AMD).However,it is still unclear how this process relates to the fate of heavy metal contaminants.The study comprehensively reports the significant role and speciation redistribution of Cu(Ⅱ)during the photochemical transformation of a Sch/tartaric acid(TA)system.Based on X-ray diffractometer and Fourier transform infrared spectra results,the presence of TA in simulated AMD significantly promoted photoreductive dissolution and phase transformation of Sch to magnetite(Mt)and goethite(Gt)under anoxic and oxic conditions,respectively.With the addition of 10-30 mg/L Cu(Ⅱ),this transformation of Sch/TA system was significantly inhibited,i.e.,only Gt occurred as product under anoxic conditions and even no phase transformation under oxic conditions.The results of EPR and adsorbed Fe(Ⅱ)indicated that the coexistence of Cu(Ⅱ)suppressed the amount of adsorbed Fe(Ⅱ)available for the transformation of Sch via competitive adsorption with Fe(Ⅱ)and inhibition of ligand-to-metal charge transfer(LMCT)of Sch-TA complexes.Chemical speciation and X-ray photoelectron spectroscopy analysis revealed the proportions of adsorbed and structural Cu(Ⅱ)of Sch/TA system were observably enhanced due to an increase in pH and recrystallization/nucleation growth of newly formed Gt.Under anoxic conditions,62.7%-75.88%of Cu(Ⅱ)was adsorbed on the mineral surface,and during the nucleation and growth of secondary mineral phases,15.49%-17.01%of Cu(Ⅱ)was incorporated into their crystal structure.The changes in distribution of Cu(Ⅱ)further suggested the photochemical transformation of Sch facilitated the sequestration of heavy metals and reduced their bioavailability.These findings enhance the understanding of role and redistribution of Cu(Ⅱ)during the transformation of Sch/LMWOA system in euphotic zone of AMD and provid insights of exploring engineered strategies of AMD remediation.展开更多
The synthesis ofα-amino acid from imines with different carbonyl sources is attractive for both synthetic organic and medicinal chemistry communities.Imines,which were easily available from the corresponding ketones ...The synthesis ofα-amino acid from imines with different carbonyl sources is attractive for both synthetic organic and medicinal chemistry communities.Imines,which were easily available from the corresponding ketones and amines,were employed as one of the most ideal precursors.Traditionally,cyanation and subsequent hydrolysis were required to install the carboxyl group^([1]).In these cases,the toxicity of the cyanation reagents limited its further synthetic applications in organic chemsitry.Besides,metal activation of imine substrates to make the organometallic intermediate and trap CO_(2) to give the desiredα-amino acid were also developed by many groups(Scheme 1A).The utilization of stoiochiometric amounts of metal reagents was required to realize the transformation.Recently,Yu reported a novel photocatalytic reductive carboxylation protocol for synthesis ofα-amino acid from imines with CO_(2)as the carbonyl source^([2]).展开更多
Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver to...Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver toxicity.Herein,the abilities of BiVO4,Ag-BiVO4,Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation（λ≥420 nm） were investigated and compared.The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry.The results showed that the presence of Ag^0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag^0 at the p-n heterojunction.Moreover,the presence of Ag^0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface.Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.展开更多
Relationships between fluorescence parameters and membrane lipid peroxidation in leaves of indica and japonica rice (Oryza sativa L.) during later growth stage were studied under chilling temperature and strong light ...Relationships between fluorescence parameters and membrane lipid peroxidation in leaves of indica and japonica rice (Oryza sativa L.) during later growth stage were studied under chilling temperature and strong light stress conditions. Results showed that D1 protein contents of PSⅡ in photosynthetic apparatus dropped, the generation of antheraxanthin (A) and zeaxanthin (Z) of xanthophyll cycle were inhibited partly, PSⅡ photochemical efficiency (F v/F m)and non-photochemical quenching (q N) were also decreased obviously. In addition, endogenous active oxygen scavenger—superoxide dismutase (SOD) reduced, superoxide anion radical (O -· 2) and malondialdehyde (MDA) accumulated, as a result, photooxidation of leaves occurred under chilling temperature and strong light stress conditions. Obvious differences in the changes of the above mentioned physiological parameters between indica and japonica rice were observed. Experiments in leaves treated with inhibitors under chilling temperature and strong light conditions showed that indica rice was more sensitive to chilling temperature with strong light and subjected to photooxidation more than japonica rice. Notable positive correlation between D1 protein contents and F v/F m or (A+Z)/(A+Z+V), and a marked negative correlation between F v/F m and MDA contents were obtained by regression analysis in indica and japonica rice during chilling temperature and strong light conditions. According to the facts mentioned above, it was inferred that PSⅡ photochemical efficiency(F v/F m) was the key index to forecast for the prediction of photooxidation under stress circumstances and the physiological basis were the synthetic capacity of D1 protein and the protection of xanthophyll cycle.展开更多
The relationships between photochemical reflectance index （PRI） and the chlorophyll fluorescence parameters were examined to assess suitability of PRI as a remote-sensing tool for the chlorophyll fluorescence parame...The relationships between photochemical reflectance index （PRI） and the chlorophyll fluorescence parameters were examined to assess suitability of PRI as a remote-sensing tool for the chlorophyll fluorescence parameters. A greenhouse experiment was conducted using cotton and peanut crops under water stress condition. Five cotton and six peanut cultivars were grown using Andosole soil in pots maintained at two water levels; the control and water stress treatment （WS） of 100 and 50% of the daily transpiration, respectively. Higher non-photochemical quenching （NPQ） was exhibited by peanut than that of cotton by the water stress. On the other hand, the decreases of the actual quantum yield of photosystem II （△F/F＇m） and PRI by the water stress in cotton were larger than those in peanut. There were positively significant correlation coefficients between PRI and △F/F＇m in cotton at noon and in the afternoon including the control and WS. The correlations of PRI with NPQ were negatively significant at noon and in the afternoon for cotton, and in the afternoon for peanut. No clear relationship was found among these parameters in the morning probably due to the diurnal increase in global solar radiation. It was concluded that there would be a possibility to detect the effects of water stress on △F/F＇m and NPQ by PRI with some exceptions, although PRI could not note varietals differences in △F/F＇m and NPQ for each treatment.展开更多
A new rhodium(Ⅱ)porphyrin complex was isolated by chromatography from the photochemical reac- tion of(μ—tetraphenylporphyrinato)bis[dicarbonylrhodium(Ⅰ)]with pyridine in benzene and has been charac- terized.From t...A new rhodium(Ⅱ)porphyrin complex was isolated by chromatography from the photochemical reac- tion of(μ—tetraphenylporphyrinato)bis[dicarbonylrhodium(Ⅰ)]with pyridine in benzene and has been charac- terized.From the results,the reaction mechanism is proposed.展开更多
The oxygen evolution, thermal dissipation, and photochemical energy storage of three hybrid poplar clones, namely the triploid clone B342, the diploid clone B11 [(Populus alba×P. glandulosa)×(P.tomentosa...The oxygen evolution, thermal dissipation, and photochemical energy storage of three hybrid poplar clones, namely the triploid clone B342, the diploid clone B11 [(Populus alba×P. glandulosa)×(P.tomentosa×P.bolleana)], and the triploid clone B346 [(P.tomentosa×P. bolleana)×(P. alba×P.glandulosa)], under light stress were studied using photoacoustics. The oxygen evolution signal and photochemical energy storage varied negatively with the pretreatment_PFD (photon flux density), whereas the thermal signal varied positively with the pretreatment_PFD. Photochemical energy storage was reallocated to PSⅡ more than to PSⅠ, while the photochemical energy storage in PSⅠ was more stable than that in PSⅡ when subjected to light stress. The inhibitors streptomycin (SM), dithiothreitol (DTT) and sodium fluoride (NaF) could all affect the oxygen evolution signal. Clones B11 and B342 were more resistant to light stress than clone B346.展开更多
In this paper we present a review of atmospheric chemistry research in China over the period 2006-2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the p...In this paper we present a review of atmospheric chemistry research in China over the period 2006-2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the polluted areas of China. Over the past decade, China has suffered severe photochemical smog and haze pollution, especially in North China, the Yangtze River Delta, and the Pearl River Delta. Much scientific work on atmospheric chemistry and physics has been done to address this large-scale, complex environmental problem. Intensive field experiments, satellite data analyses, and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China. In addition to strong emissions of primary pollutants, photochemical and heterogeneous reactions play key roles in the formation of complex pollution. More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban, regional, and global scales.展开更多
Oxygenated volatile organic compounds(OVOCs) are key intermediates in the atmospheric photooxidation process. To further study the primary and secondary sources of OVOCs,their ambient levels were monitored using a pro...Oxygenated volatile organic compounds(OVOCs) are key intermediates in the atmospheric photooxidation process. To further study the primary and secondary sources of OVOCs,their ambient levels were monitored using a proton-transfer reaction mass spectrometer(PTR-MS) at an urban site in the Pearl River Delta of China. Continuous monitoring campaigns were conducted in the spring, summer, fall, and winter of 2016. Among the six types of OVOC species, the mean concentrations of methanol were the highest in each season(up to 13–20 ppbv), followed by those of acetone, acetaldehyde and acetic acid(approximately 2–4 ppbv), while those of formic acid and methyl ethyl ketone(MEK) were the lowest(approximately 1–2 ppbv). As observed from a diurnal variation chart, the OVOCs observed in Shenzhen may have been affected by numerous factors such as their primary and secondary sources and photochemical consumption. The photochemical age-based parameterization method was used to apportion the sources of ambient OVOCs. Methanol had significant anthropogenic primary sources but negligible anthropogenic secondary sources during all of the seasons. Acetone, MEK and acetic acid were mostly attributed to anthropogenic primary sources during each season with smaller contributions from anthropogenic secondary sources. Acetaldehyde had similar contributions from both anthropogenic secondary and anthropogenic primary sources throughout the year.Meanwhile, anthropogenic primary sources contributed the most to formic acid.展开更多
A surface femtosecond two-photon photoemission （2PPE） spectrometer devoted to the study of ultrafast excited electron dynamics and photochemical kinetics on metal and metal oxide surfaces has been constructed. Low e...A surface femtosecond two-photon photoemission （2PPE） spectrometer devoted to the study of ultrafast excited electron dynamics and photochemical kinetics on metal and metal oxide surfaces has been constructed. Low energy photoelectrons are measured using a hemispherical electron energy analyzer with an imaging detector that allows us to detect the energy and the angular distributions of the photoelectrons simultaneously. A Mach-Zehnder interferom- eter was built for the time-resolved 2PPE （TR-2PPE） measurement to study ultrafast surface excited electron dynamics, which was demonstrated on the Cu（111） surface. A scheme for measuring time-dependent 2PPE （TD-2PPE） spectra has also been developed for studies of surface photochemistry. This technique has been applied to a preliminary study on the photochemical kinetics on ethanol/TiO2（110）. We have also shown that the ultrafast dynamics of photoinduced surface excited resonances can be investigated in a reliable way by combining the TR-2PPE and TD-2PPE techniques.展开更多
The photochemical air pollution in Xigu district of Lanshou city, Gansu Province was studied during a period of 1981-1984. The extremely high NMHC/NOx ratio and ozone level elevation after rain have been noticed. A se...The photochemical air pollution in Xigu district of Lanshou city, Gansu Province was studied during a period of 1981-1984. The extremely high NMHC/NOx ratio and ozone level elevation after rain have been noticed. A series of outdoor and indoor reaction chamber simulation experiments conducted in order to understand the specific conditions. The ozone formation under NMHC/NOx condition and the possible reason for high ozone concentration after rain are discussed.展开更多
Comprehensive air quality model with extensions(CAMx)-decoupled direct method(DDM)was used to simulate ozone-NO_(x)-VOCs sensitivity of for May-November in 2016-2018 in China.Based on the relationship between the simu...Comprehensive air quality model with extensions(CAMx)-decoupled direct method(DDM)was used to simulate ozone-NO_(x)-VOCs sensitivity of for May-November in 2016-2018 in China.Based on the relationship between the simulated ozone(O_(3))sensitivity values and the ratio of formaldehyde(HCHO)to NO_(2)(FNR)and the ratio of production rate of hydrogen peroxide(H_(2)O_(2))to production rate of nitric acid(HNO_(3))(P_(H_(2)O_(2))/P_(HNO_(3))),the localized range of FNR and P_(H_(2)O_(2))/P_(HNO_(3))thresholds in different regions in China were obtained.The overall simulated FNR values are about 1.640-2.520,and P_(H_(2)O_(2))/P_(HNO_(3))values are about 0.540-0.830 for the transition regime.Model simulated O_(3)sensitivities or region specific FNR or P_(H_(2)O_(2))/P_(HNO_(3))thresholds should be applied to ensure the accurate local O3 sensitivity regimes.Using the tropospheric column FNR values from ozone monitoring instrument(OMI)satellite data as an indicator with the simulated threshold values,the spatial distributions of O_(3)formation regimes in China are determined.The O_(3)sensitivity regimes from eastern to central China are gradually from VOC-limited,transition to NO_(x)-limited spatially,and moving toward to transition or NO_(x)-limited regime from 2005 to 2019 temporally.展开更多
Air pollution in modern city and industrial zones has become a serious public concern in recent years in China. Significance of air quality assessment and emission control strategy design is increasing. Most studies i...Air pollution in modern city and industrial zones has become a serious public concern in recent years in China. Significance of air quality assessment and emission control strategy design is increasing. Most studies in China focus on particulate matter(PM), especially PM2.5, while few account for photochemical secondary air pollutions represented by ozone(O3). In this paper, a procedure for air quality simulation with comprehensive air quality model with extensions(CAMx) is demonstrated for studying the photochemical process and ozone generation in the troposphere. As a case study, the CAMx photochemical grid model is used to model ozone over southern part of Beijing city in winter, 2011. The input parameters to CAMx include emission sources, meteorology field data, terrain definition, photolysis status, initial and boundary conditions. The simulation results are verified by theoretical analysis of the ozone generation tendency. The simulated variation tendency of domain-wide average value of hourly ozone concentration coincides reasonably well with the theoretical analysis on the atmospheric photochemical process, demonstrating the effectiveness of the procedure. An integrated model system that cooperates with CAMx will be established in our future work.展开更多
Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites （Pingtung City, Chao-Chou Town, and Kenting Town） in Pingtung County in southern Taiwan during 2003 and 200...Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites （Pingtung City, Chao-Chou Town, and Kenting Town） in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds （VOC）-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators （H202, HNO3, and NOy） were conducted, and simulated three transition ranges of H202/HNO3 （0.5-0.8）, O3/HNO3 （10.3-16.2） and O3/NOy （5.7-10.8） were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.展开更多
Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy...Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.展开更多
The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and hum...The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.展开更多
The rational design of photochemical molecular device(PMD)and its hybrid system has great potential in improving the activity of photocatalytic hydrogen production.A series of Pd6L3 type metal-organic cages,denoted as...The rational design of photochemical molecular device(PMD)and its hybrid system has great potential in improving the activity of photocatalytic hydrogen production.A series of Pd6L3 type metal-organic cages,denoted as MOC-Py-M(M=H,Cu,and Zn),are designed for PMDs by combining metalloporphyrin-based ligands with catalytically active Pd^(2+)centers.These metal-organic cages(MOCs)are first successfully hybridized with graphitic carbon nitride(g-C_(3)N_(4))to form direct Z-scheme heterogeneous MOC-Py-M/g-C_(3)N_(4)(M=H,Cu,and Zn)photocatalysts via π-πinteractions.Benefiting from its better light absorption ability,the MOC-Py-Zn/g-C_(3)N_(4) catalyst exhibits high H_(2) production activity under visible light(10348μmol g^(-1) h^(-1)),far superior to MOC-Py-H/g-C_(3)N_(4) and MOC-Py-Cu/g-C_(3)N_(4).Moreover,the MOC-Py-Zn/g-C_(3)N_(4) system obtains an enhanced turn over number(TON)value of 32616 within 100 h,outperforming the homogenous MOC-Py-Zn(TON of 507 within 100 h),which is one of the highest photochemical hybrid systems based on MOC for visible-light-driven hydrogen generation.This confirms the direct Z-scheme heterostructure can promote effective charge transfer,expand the visible light absorption region,and protect the cages from decomposition in MOC-Py-Zn/g-C_(3)N_(4).This work presents a creative example that direct Z-scheme PMD-based systems for effective and persistent hydrogen generation from water under visible light are obtained by heterogenization approach using homogeneous porphyrin-based MOCs and g-C_(3)N_(4) semiconductors.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21976045 and 22076112)China Scholarship Council(CSC)Scholarship(Nos.202208610125 and 202308610123)+1 种基金Shaanxi Key Laboratory of Environmental Monitoring and Forewarning of Trace Pollutants(No.SHJKFJJ202318)the Key Research and Development Program of Shaanxi Province(No.2024SF-YBXM-567).
文摘Acid-base dissociable antibiotic-metal complexes are known to be emerging contaminants in the aquatic environments.However,little information is available on the photochemical properties and toxicity of these complex forms.This study investigated the spectral properties of three fluoroquinolones(FQs)with and without metal ions Fe(III),Cu(II),and Al(III)in solutions under different pH conditions,as well as evaluated the changes in toxicity due to the complex with thesemetal ions using luminescent bacteria(vibrio fischeri).FQs showed a higher tendency to coordinate metal ions under alkaline conditions compared to neutral and acidic conditions,and the formation of complexes weakened the ultravioletabsorbing ability of FQs.At pH=7.0,Cu(II)quenched the fluorescence intensity of FQs.Moreover,their Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were explored,revealing that the coordination sites of Cu(II)in three FQs were situated in a bidentate manner through the oxygen atom of the deprotonated carboxyl group and cyclic carbonyl oxygen atom.This conclusion was further verified by the theory of molecular surface electrostatic potential.In addition,except for complexes of ciprofloxacin-metals,enhanced toxicity of FQs upon coordination with Fe(III)was observed,while reduced toxicity was found for coordination with Cu(II)and Al(III).These results are important for accurately evaluating the photochemical behavior and risk of these antibiotics in aquatic environments contaminated with metal ions.
基金financially supported by the National Natural Science Foundation of China(Nos.22104112 and 22374110)the Fundamental Research Funds for the Central Universities。
文摘The investigation of reaction kinetics is the key to understanding the nature of reaction processes.However,monitoring fast photochemical reactions by mass spectrometry remains challenging.Herein,we developed an optical focusing inductive electrospray(OF-iESI)mass spectrometry platform for real-time and in-situ photoreaction monitoring.Coaxial irradiation from back of nanoelectrospray emitter with a taper section was utilized,so the emitter could act as optical lens to help achieving much larger optical power density at emitter tip compared to other sections,which allowed for in-situ reaction monitoring of photoreactions.Through theoretical calculations,the highest optical power density region volume was ca.45 nL.We also integrated a controller for the laser source(450 nm),enabling the modulation of pulse duration(>1 ms).This facilitates the study of photochemical reaction kinetics.The in-situ capability of this device was proved by capturing the short-lived photogenerated intermediates during the dehydrogenation of tetrahydroquinoline.This device was further used to investigate the kinetics of triplet energy transfer based Paternò-Büchi reaction.The reaction order has hitherto remained undetermined while the result of OF-iESI suggested it followed pseudo-second-order reaction kinetics.The short-lived donor-acceptor collision complex intermediate was also successfully identified by tandem mass spectrometry.
基金supported by the National Key R&D Program of China(No.2023YFC3705801)the National Natural Science Foundation of China(No.42177085).
文摘Substantial effects of photochemical reaction losses of volatile organic compounds(VOCs)on factor profiles can be investigated by comparing the differences between daytime and nighttime dispersion-normalized VOC data resolved profiles.Hourly speciated VOC data measured in Shijiazhuang,China from May to September 2021 were used to conduct study.The mean VOC concentration in the daytime and at nighttime were 32.8 and 36.0 ppbv,respectively.Alkanes and aromatics concentrations in the daytime(12.9 and 3.08 ppbv)were lower than nighttime(15.5 and 3.63 ppbv),whereas that of alkenes showed the opposite tendency.The concentration differences between daytime and nighttime for alkynes and halogenated hydrocarbonswere uniformly small.The reactivities of the dominant species in factor profiles for gasoline emissions,natural gas and diesel vehicles,and liquefied petroleum gas were relatively low and their profiles were less affected by photochemical losses.Photochemical losses produced a substantial impact on the profiles of solvent use,petrochemical industry emissions,combustion sources,and biogenic emissions where the dominant species in these factor profiles had high reactivities.Although the profile of biogenic emissions was substantially affected by photochemical loss of isoprene,the low emissions at nighttime also had an important impact on its profile.Chemical losses of highly active VOC species substantially reduced their concentrations in apportioned factor profiles.This study results were consistent with the analytical results obtained through initial concentration estimation,suggesting that the initial concentration estimation could be the most effective currently availablemethod for the source analyses of active VOCs although with uncertainty.
基金financially supported by the National Natural Science Foundation of China(No.U21A2034)the Guangdong Special Support Plan for Innovation Teams(No.2019BT02L218).
文摘Light exposure can accelerate phase transformation of Schwertmannite(Sch)coexisting with lowmolecular-weight organic acids(LMWOAs),affecting the cycling of Fe in acid mine drainage(AMD).However,it is still unclear how this process relates to the fate of heavy metal contaminants.The study comprehensively reports the significant role and speciation redistribution of Cu(Ⅱ)during the photochemical transformation of a Sch/tartaric acid(TA)system.Based on X-ray diffractometer and Fourier transform infrared spectra results,the presence of TA in simulated AMD significantly promoted photoreductive dissolution and phase transformation of Sch to magnetite(Mt)and goethite(Gt)under anoxic and oxic conditions,respectively.With the addition of 10-30 mg/L Cu(Ⅱ),this transformation of Sch/TA system was significantly inhibited,i.e.,only Gt occurred as product under anoxic conditions and even no phase transformation under oxic conditions.The results of EPR and adsorbed Fe(Ⅱ)indicated that the coexistence of Cu(Ⅱ)suppressed the amount of adsorbed Fe(Ⅱ)available for the transformation of Sch via competitive adsorption with Fe(Ⅱ)and inhibition of ligand-to-metal charge transfer(LMCT)of Sch-TA complexes.Chemical speciation and X-ray photoelectron spectroscopy analysis revealed the proportions of adsorbed and structural Cu(Ⅱ)of Sch/TA system were observably enhanced due to an increase in pH and recrystallization/nucleation growth of newly formed Gt.Under anoxic conditions,62.7%-75.88%of Cu(Ⅱ)was adsorbed on the mineral surface,and during the nucleation and growth of secondary mineral phases,15.49%-17.01%of Cu(Ⅱ)was incorporated into their crystal structure.The changes in distribution of Cu(Ⅱ)further suggested the photochemical transformation of Sch facilitated the sequestration of heavy metals and reduced their bioavailability.These findings enhance the understanding of role and redistribution of Cu(Ⅱ)during the transformation of Sch/LMWOA system in euphotic zone of AMD and provid insights of exploring engineered strategies of AMD remediation.
文摘The synthesis ofα-amino acid from imines with different carbonyl sources is attractive for both synthetic organic and medicinal chemistry communities.Imines,which were easily available from the corresponding ketones and amines,were employed as one of the most ideal precursors.Traditionally,cyanation and subsequent hydrolysis were required to install the carboxyl group^([1]).In these cases,the toxicity of the cyanation reagents limited its further synthetic applications in organic chemsitry.Besides,metal activation of imine substrates to make the organometallic intermediate and trap CO_(2) to give the desiredα-amino acid were also developed by many groups(Scheme 1A).The utilization of stoiochiometric amounts of metal reagents was required to realize the transformation.Recently,Yu reported a novel photocatalytic reductive carboxylation protocol for synthesis ofα-amino acid from imines with CO_(2)as the carbonyl source^([2]).
基金supported by the National Natural Science Foundation of China (21677086, 21407092, 21377067, 21577078)the Natural Science Foundation for Innovation Group of Hubei Province, China (2015CFA021)~~
文摘Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver toxicity.Herein,the abilities of BiVO4,Ag-BiVO4,Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation（λ≥420 nm） were investigated and compared.The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry.The results showed that the presence of Ag^0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag^0 at the p-n heterojunction.Moreover,the presence of Ag^0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface.Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.
文摘Relationships between fluorescence parameters and membrane lipid peroxidation in leaves of indica and japonica rice (Oryza sativa L.) during later growth stage were studied under chilling temperature and strong light stress conditions. Results showed that D1 protein contents of PSⅡ in photosynthetic apparatus dropped, the generation of antheraxanthin (A) and zeaxanthin (Z) of xanthophyll cycle were inhibited partly, PSⅡ photochemical efficiency (F v/F m)and non-photochemical quenching (q N) were also decreased obviously. In addition, endogenous active oxygen scavenger—superoxide dismutase (SOD) reduced, superoxide anion radical (O -· 2) and malondialdehyde (MDA) accumulated, as a result, photooxidation of leaves occurred under chilling temperature and strong light stress conditions. Obvious differences in the changes of the above mentioned physiological parameters between indica and japonica rice were observed. Experiments in leaves treated with inhibitors under chilling temperature and strong light conditions showed that indica rice was more sensitive to chilling temperature with strong light and subjected to photooxidation more than japonica rice. Notable positive correlation between D1 protein contents and F v/F m or (A+Z)/(A+Z+V), and a marked negative correlation between F v/F m and MDA contents were obtained by regression analysis in indica and japonica rice during chilling temperature and strong light conditions. According to the facts mentioned above, it was inferred that PSⅡ photochemical efficiency(F v/F m) was the key index to forecast for the prediction of photooxidation under stress circumstances and the physiological basis were the synthetic capacity of D1 protein and the protection of xanthophyll cycle.
文摘The relationships between photochemical reflectance index （PRI） and the chlorophyll fluorescence parameters were examined to assess suitability of PRI as a remote-sensing tool for the chlorophyll fluorescence parameters. A greenhouse experiment was conducted using cotton and peanut crops under water stress condition. Five cotton and six peanut cultivars were grown using Andosole soil in pots maintained at two water levels; the control and water stress treatment （WS） of 100 and 50% of the daily transpiration, respectively. Higher non-photochemical quenching （NPQ） was exhibited by peanut than that of cotton by the water stress. On the other hand, the decreases of the actual quantum yield of photosystem II （△F/F＇m） and PRI by the water stress in cotton were larger than those in peanut. There were positively significant correlation coefficients between PRI and △F/F＇m in cotton at noon and in the afternoon including the control and WS. The correlations of PRI with NPQ were negatively significant at noon and in the afternoon for cotton, and in the afternoon for peanut. No clear relationship was found among these parameters in the morning probably due to the diurnal increase in global solar radiation. It was concluded that there would be a possibility to detect the effects of water stress on △F/F＇m and NPQ by PRI with some exceptions, although PRI could not note varietals differences in △F/F＇m and NPQ for each treatment.
基金Project Supported by Science Research Foundation of Zhongshan University,National Natural Science Foundation of P.R.China and Resarch Fund of Royal Society of Chemistry
文摘A new rhodium(Ⅱ)porphyrin complex was isolated by chromatography from the photochemical reac- tion of(μ—tetraphenylporphyrinato)bis[dicarbonylrhodium(Ⅰ)]with pyridine in benzene and has been charac- terized.From the results,the reaction mechanism is proposed.
文摘The oxygen evolution, thermal dissipation, and photochemical energy storage of three hybrid poplar clones, namely the triploid clone B342, the diploid clone B11 [(Populus alba×P. glandulosa)×(P.tomentosa×P.bolleana)], and the triploid clone B346 [(P.tomentosa×P. bolleana)×(P. alba×P.glandulosa)], under light stress were studied using photoacoustics. The oxygen evolution signal and photochemical energy storage varied negatively with the pretreatment_PFD (photon flux density), whereas the thermal signal varied positively with the pretreatment_PFD. Photochemical energy storage was reallocated to PSⅡ more than to PSⅠ, while the photochemical energy storage in PSⅠ was more stable than that in PSⅡ when subjected to light stress. The inhibitors streptomycin (SM), dithiothreitol (DTT) and sodium fluoride (NaF) could all affect the oxygen evolution signal. Clones B11 and B342 were more resistant to light stress than clone B346.
基金funded by the China Meteorological Administration (Grant Nos. GYHY 200706005, GYHY 201106023 and GYHY 201206015)
文摘In this paper we present a review of atmospheric chemistry research in China over the period 2006-2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the polluted areas of China. Over the past decade, China has suffered severe photochemical smog and haze pollution, especially in North China, the Yangtze River Delta, and the Pearl River Delta. Much scientific work on atmospheric chemistry and physics has been done to address this large-scale, complex environmental problem. Intensive field experiments, satellite data analyses, and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China. In addition to strong emissions of primary pollutants, photochemical and heterogeneous reactions play key roles in the formation of complex pollution. More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban, regional, and global scales.
基金supported by the Ministry of Science and Technology of China (Nos.2017YFC0210004,2014BAC21B01)the Science and Technology Plan of Shenzhen Municipality (Nos.JCYJ20170412150626172,JCYJ20160122105855253)
文摘Oxygenated volatile organic compounds(OVOCs) are key intermediates in the atmospheric photooxidation process. To further study the primary and secondary sources of OVOCs,their ambient levels were monitored using a proton-transfer reaction mass spectrometer(PTR-MS) at an urban site in the Pearl River Delta of China. Continuous monitoring campaigns were conducted in the spring, summer, fall, and winter of 2016. Among the six types of OVOC species, the mean concentrations of methanol were the highest in each season(up to 13–20 ppbv), followed by those of acetone, acetaldehyde and acetic acid(approximately 2–4 ppbv), while those of formic acid and methyl ethyl ketone(MEK) were the lowest(approximately 1–2 ppbv). As observed from a diurnal variation chart, the OVOCs observed in Shenzhen may have been affected by numerous factors such as their primary and secondary sources and photochemical consumption. The photochemical age-based parameterization method was used to apportion the sources of ambient OVOCs. Methanol had significant anthropogenic primary sources but negligible anthropogenic secondary sources during all of the seasons. Acetone, MEK and acetic acid were mostly attributed to anthropogenic primary sources during each season with smaller contributions from anthropogenic secondary sources. Acetaldehyde had similar contributions from both anthropogenic secondary and anthropogenic primary sources throughout the year.Meanwhile, anthropogenic primary sources contributed the most to formic acid.
文摘A surface femtosecond two-photon photoemission （2PPE） spectrometer devoted to the study of ultrafast excited electron dynamics and photochemical kinetics on metal and metal oxide surfaces has been constructed. Low energy photoelectrons are measured using a hemispherical electron energy analyzer with an imaging detector that allows us to detect the energy and the angular distributions of the photoelectrons simultaneously. A Mach-Zehnder interferom- eter was built for the time-resolved 2PPE （TR-2PPE） measurement to study ultrafast surface excited electron dynamics, which was demonstrated on the Cu（111） surface. A scheme for measuring time-dependent 2PPE （TD-2PPE） spectra has also been developed for studies of surface photochemistry. This technique has been applied to a preliminary study on the photochemical kinetics on ethanol/TiO2（110）. We have also shown that the ultrafast dynamics of photoinduced surface excited resonances can be investigated in a reliable way by combining the TR-2PPE and TD-2PPE techniques.
文摘The photochemical air pollution in Xigu district of Lanshou city, Gansu Province was studied during a period of 1981-1984. The extremely high NMHC/NOx ratio and ozone level elevation after rain have been noticed. A series of outdoor and indoor reaction chamber simulation experiments conducted in order to understand the specific conditions. The ozone formation under NMHC/NOx condition and the possible reason for high ozone concentration after rain are discussed.
基金supported by National Key Research and Development Project(Nos.2018YFC0213504,2017YFC0213003,2016YFC0208905)
文摘Comprehensive air quality model with extensions(CAMx)-decoupled direct method(DDM)was used to simulate ozone-NO_(x)-VOCs sensitivity of for May-November in 2016-2018 in China.Based on the relationship between the simulated ozone(O_(3))sensitivity values and the ratio of formaldehyde(HCHO)to NO_(2)(FNR)and the ratio of production rate of hydrogen peroxide(H_(2)O_(2))to production rate of nitric acid(HNO_(3))(P_(H_(2)O_(2))/P_(HNO_(3))),the localized range of FNR and P_(H_(2)O_(2))/P_(HNO_(3))thresholds in different regions in China were obtained.The overall simulated FNR values are about 1.640-2.520,and P_(H_(2)O_(2))/P_(HNO_(3))values are about 0.540-0.830 for the transition regime.Model simulated O_(3)sensitivities or region specific FNR or P_(H_(2)O_(2))/P_(HNO_(3))thresholds should be applied to ensure the accurate local O3 sensitivity regimes.Using the tropospheric column FNR values from ozone monitoring instrument(OMI)satellite data as an indicator with the simulated threshold values,the spatial distributions of O_(3)formation regimes in China are determined.The O_(3)sensitivity regimes from eastern to central China are gradually from VOC-limited,transition to NO_(x)-limited spatially,and moving toward to transition or NO_(x)-limited regime from 2005 to 2019 temporally.
文摘Air pollution in modern city and industrial zones has become a serious public concern in recent years in China. Significance of air quality assessment and emission control strategy design is increasing. Most studies in China focus on particulate matter(PM), especially PM2.5, while few account for photochemical secondary air pollutions represented by ozone(O3). In this paper, a procedure for air quality simulation with comprehensive air quality model with extensions(CAMx) is demonstrated for studying the photochemical process and ozone generation in the troposphere. As a case study, the CAMx photochemical grid model is used to model ozone over southern part of Beijing city in winter, 2011. The input parameters to CAMx include emission sources, meteorology field data, terrain definition, photolysis status, initial and boundary conditions. The simulation results are verified by theoretical analysis of the ozone generation tendency. The simulated variation tendency of domain-wide average value of hourly ozone concentration coincides reasonably well with the theoretical analysis on the atmospheric photochemical process, demonstrating the effectiveness of the procedure. An integrated model system that cooperates with CAMx will be established in our future work.
基金supported by the Environmental Protection Bureau,Government of Pingtung County,Taiwan,China
文摘Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites （Pingtung City, Chao-Chou Town, and Kenting Town） in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds （VOC）-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators （H202, HNO3, and NOy） were conducted, and simulated three transition ranges of H202/HNO3 （0.5-0.8）, O3/HNO3 （10.3-16.2） and O3/NOy （5.7-10.8） were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.
文摘Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.
基金supported by the Central Level,Scientific Research Institutes for Basic R&D Special Fund Business,China(No.2021-JY-16)the National Natural Science Foundation of China(Nos.42075182 and 2130721)+1 种基金the National Research Program for Key Issue in Air Pollution Control(No.DQGG2021101)the National Key Research and Development Program of China(No.2019YFC0214800)。
文摘The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.
文摘The rational design of photochemical molecular device(PMD)and its hybrid system has great potential in improving the activity of photocatalytic hydrogen production.A series of Pd6L3 type metal-organic cages,denoted as MOC-Py-M(M=H,Cu,and Zn),are designed for PMDs by combining metalloporphyrin-based ligands with catalytically active Pd^(2+)centers.These metal-organic cages(MOCs)are first successfully hybridized with graphitic carbon nitride(g-C_(3)N_(4))to form direct Z-scheme heterogeneous MOC-Py-M/g-C_(3)N_(4)(M=H,Cu,and Zn)photocatalysts via π-πinteractions.Benefiting from its better light absorption ability,the MOC-Py-Zn/g-C_(3)N_(4) catalyst exhibits high H_(2) production activity under visible light(10348μmol g^(-1) h^(-1)),far superior to MOC-Py-H/g-C_(3)N_(4) and MOC-Py-Cu/g-C_(3)N_(4).Moreover,the MOC-Py-Zn/g-C_(3)N_(4) system obtains an enhanced turn over number(TON)value of 32616 within 100 h,outperforming the homogenous MOC-Py-Zn(TON of 507 within 100 h),which is one of the highest photochemical hybrid systems based on MOC for visible-light-driven hydrogen generation.This confirms the direct Z-scheme heterostructure can promote effective charge transfer,expand the visible light absorption region,and protect the cages from decomposition in MOC-Py-Zn/g-C_(3)N_(4).This work presents a creative example that direct Z-scheme PMD-based systems for effective and persistent hydrogen generation from water under visible light are obtained by heterogenization approach using homogeneous porphyrin-based MOCs and g-C_(3)N_(4) semiconductors.
