Photocatalytic disinfection is an eco-friendly strategy for countering bacterial pollution in aquatic environments.Numerous strategies have been devised to facilitate the generation of reactive oxygen species(ROS)with...Photocatalytic disinfection is an eco-friendly strategy for countering bacterial pollution in aquatic environments.Numerous strategies have been devised to facilitate the generation of reactive oxygen species(ROS)within photocatalysts,ultimately leading to the eradication of bacteria.However,the significance of the physical morphology of photocatalysts in the context of sterilization is frequently obscured,and the progress in the development of physical-chemical synergistic sterilization photocatalysts has been relatively limited.Herein,graphitic carbon nitride(g-C_(3)N_(4))is chemically protonated to expose more sharp edges.PL fluorescence and EIS results indicate that the protonation can accelerate photogenerated carrier separation and enhance ROS production.Meanwhile,the sharp edges on the protonated g-C_(3)N_(4)facilitate the physical disruption of cell walls for further promoting oxidative damage.Protonated C_(3)N_(4)demonstrated superior bactericidal performance than that of pristine g-C_(3)N_(4),effectively eliminating Escherichia coli within 40 minutes under irradiation.This work highlights the significance of incorporating physical and chemical synergies in photocatalyst design to enhance the disinfection efficiency of photocatalysis.展开更多
New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by...New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by EPMA, AAS, XRD, IR, DTA and so on. The structure may be described as treble perovskite sheets [Sr2Nb3O10]- interleaved with K+ ,H3O + or H+. These new compounds are new members of the Dion-Jacob-sonseries with n=3 for the general formula M[An-1 NbnO3n+1], and their indexed X-ray powder diffraction data were first reported in the paper.展开更多
Formation and dissociation mechanisms of C-C＋ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environmen...Formation and dissociation mechanisms of C-C＋ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environment, a cytosine monomer is first protonated and then dimerized with an unprotonated cytosine monomer to form a C-C＋ base pair; in an alkaline environment, a protonated cytosine dimer is first unprotonated and then dissociated into two cytosine monomers. In addition, the force for detaching a C-C＋ base pair was found to be inversely proportional to the distance between the two cytosine monomers. These results provide a microscopic mechanism to qualitatively explain the experimentally observed reversible formation and dissociation of i-motifs.展开更多
Rhodopsin is a seven-helical transmembrane protein with a retinal chromophore covalently bound to a conserved lysine in helix G via a retinal protonated Schiff base(RPSB).Microbial rhodopsins absorb light through chro...Rhodopsin is a seven-helical transmembrane protein with a retinal chromophore covalently bound to a conserved lysine in helix G via a retinal protonated Schiff base(RPSB).Microbial rhodopsins absorb light through chromophore and play a fundamental role in optogenetics.Numerous microbial rhodopsins have been discovered,contributing to diverse functions and colors.Solid-state NMR spectroscopy has been instrumental in elucidating the conformation of chromophores and the three-dimensional structure of microbial rhodopsins.This review focuses on the 15N chemical shift values of RPSB and summarizes recent progress in the field.We displayed the correlation between the 15N isotropic chemical shift values of RPSB and the maximum absorption wavelength of rhodopsin using solid-state NMR spectroscopy.展开更多
A modified method for preparation and purification of Schiff base and protonated Schiff base from 9-cis-retinal has been suggested. Reaction took place in chloroform phase and purification was conducted by using water...A modified method for preparation and purification of Schiff base and protonated Schiff base from 9-cis-retinal has been suggested. Reaction took place in chloroform phase and purification was conducted by using water to remove the excess solvent, base and acid.展开更多
Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to real...Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to realize carbon-free hydrogen production remains a challenge.Heterojunction photocatalysts with well-defined dimensionality and perfectly matched interfaces are promising for achieving highly efficient solar-to-hydrogen conversion.Herein,we report the fabrication of a novel type of protonated graphitic carbon nitride(PCN)/Ti3C2 MXene heterojunctions with strong interfacial interactions.As expected,the two-dimensional(2D)PCN/2D Ti3C2 MXene interface heterojunction achieves a highly improved hydrogen evolution rate(2181μmol∙g‒1)in comparison with bulk g-C3N4(393μmol∙g‒1)and protonated g-C3N4(816μmol∙g‒1).The charge-regulated surfaces of PCN and the accelerated charge transport at the face-to-face 2D/2D Schottky heterojunction interface are the major contributors to the excellent hydrogen evolution performance of the composite photocatalyst.展开更多
Infrared multiple photon dissociation （IRMPD） spectroscopic and theoretical studies of protonated homodimers of amino acids generated by electrospray ionization in the gas phase have been reviewed. Results show that...Infrared multiple photon dissociation （IRMPD） spectroscopic and theoretical studies of protonated homodimers of amino acids generated by electrospray ionization in the gas phase have been reviewed. Results show that proton affinity （PA） may be applied as a probe to predict their structural type： salt- bridged or charge-solvated. Proline can be viewed as a reference. For an amino acid with a PA value higher than that of proline, the most stable conformation of its protonated homodimer tends to prefer salt- bridged conformation; otherwise, charge-solvated conformation is expected to be the most stable. However, side chain effects may cause the inaccuracy in structural determination due to the strong interactions with the charge, which makes the charge-solvated structure more stable even for species with high PA values. Temperature effect on distribution of different isomers is also very important. In lots of cases, the coexistence of multiple isomers is general, which makes the explanation of an overall IRMPD spectrum difficult. So a statistical view on the distribution of optimized isomers is very helpful.展开更多
The low energy collisioninduced dissociation, linked scan techniques and isotopic labeling experiment were used to investigate the unimolecular fragmentation of protonated N-hydroxyphthalimide under electron impact a...The low energy collisioninduced dissociation, linked scan techniques and isotopic labeling experiment were used to investigate the unimolecular fragmentation of protonated N-hydroxyphthalimide under electron impact and chemical ionization conditions. It was found that this compound shows an unusual reactivity towards protonation. Two possible sites of protonation have been proposed to explain the corresponding fragmentation processes, one is that the protonation takes place on the oxygen atom of hydroxyl group, resulting in the loss of water and the other is the formation of an intermediary protonbound complex in the fragmentation process, giving rise to the fragment ions of m/z 133 and m/z 135. The results show both cases are coexistence in the fragmentations of protonated N-hydroxyphthalimide, and the unimolecular fragmentation pathways are available.展开更多
Density functional calculations are used to determine structural and electronic properties of P4,P4O6,P4O10,P20O30 and P20O50 clusters and their protonated derivatives.These oxygen-rich phosphorus oxides are predicted...Density functional calculations are used to determine structural and electronic properties of P4,P4O6,P4O10,P20O30 and P20O50 clusters and their protonated derivatives.These oxygen-rich phosphorus oxides are predicted to have relatively high stabilities with respect to their components P4 and O2,and their unsaturated P and end-on O atoms as the proton acceptor can accommodate multiple protons to generate highly positively charged cationic clusters,such as P20O30H1010＋.Calculations indicate that P4O6 and P20O30 have higher reactivity toward the proton capture than the P4,P4O10 and P20O50 clusters,and the most stable protonated clusters among these different series of cationic clusters are P4H2……2＋,P4O6H2^2＋,P4O10H3^3＋,P20O30H4^4＋ and P20O50H4^4＋,respectively.The cage skeleton of the phosphorus oxide clusters shows high stability for the consecutive protonation,and the unsymmetrical stretching of the skeletal P-O bond and the wagging mode of P-H coupled with the P-O bond stretching have strong adsorptions.These computational findings are useful for further experimental and theoretical studies of novel phosphorus oxide clusters and their highly positively charged derivatives.展开更多
Covalent organic frameworks(COFs)are emerging as promising photocatalysts owing to their tailorable structures,exceptional crystallinity,and robustness.However,the photocatalytic performance of COFs is limited by fast...Covalent organic frameworks(COFs)are emerging as promising photocatalysts owing to their tailorable structures,exceptional crystallinity,and robustness.However,the photocatalytic performance of COFs is limited by fast charge recombination and inefficient charge migration.Herein,a novel post-synthetic partial protonation strategy is proposed to construct COFs with asymmetric unprotonated/protonated homojunctions,which endow them with an enlarged molecular dipole moment,thereby generating a strong built-in electric field that significantly enhances the charge separation and transport efficiencies in COFs.In addition,the protonation process extends the light absorption range and improves the hydrophilicity of COFs.The photocatalytic hydrogen evolution rate of the partially protonated TPE-COF and ETTBA-COF is enhanced by 88-and 175-fold relative to their pristine counterparts,4.3 and 2.48 times those of fully protonated counterparts,respectively.Our results clearly demonstrate the pivotal role of the asymmetric unprotonated/protonated homojunctions within COFs in the photocatalytic hydrogen evolution.This post-synthetic partial protonation strategy provides a novel paradigm for establishing internal electric fields within COFs.展开更多
In this work, we demonstrated the successful construction of metal-free zero- dimensional/two-dimensional carbon nanodot （CND）-hybridized protonatedg=C3N4 （pCN） （CND/pCN） heterojunction photocatalysts b; means o...In this work, we demonstrated the successful construction of metal-free zero- dimensional/two-dimensional carbon nanodot （CND）-hybridized protonatedg=C3N4 （pCN） （CND/pCN） heterojunction photocatalysts b; means of electrostatic attraction. We experimentally found that CNDs with an average diameter of 4.4 nm were uniformly distributed on the surface of pCN using electron microscopy analysis. The CND/pCN-3 sample with a CND content of 3 wt.% showed thehighest catalytic activity in the CO2 photoreduction process under visible and simulated solar light. This process results in the evolution of CH4 and CO. Thetotal amounts of CH4 and CO generated by the CND/pCN-3 photocatalyst after 10 h of visible-light activity were found to be 29.23 and 58.82 molgcatalyst-1, respectively. These values were 3.6 and 2.28 times higher, respectively, than thearn＊ounts generated when using pCN alone. The corresponding apparent quantum efficiency （AQE） was calculated to be 0.076%. Furthermore, the CND/pCN-3 sample demonstrated high stability and durability after four consecutive photoreaction cycles, with no significant decrease in the catalytic activity.展开更多
Ordered thin organic films deposited on solid substrates by the Langmuir-Blodgett(LB) technique have attracted much attention because of their possibility of being applied tofunctional molecular device architectures, ...Ordered thin organic films deposited on solid substrates by the Langmuir-Blodgett(LB) technique have attracted much attention because of their possibility of being applied tofunctional molecular device architectures, such as electronic, nonlinear optical and bio-logical sensors. Very elegant work has been carried out by Kuhn and his展开更多
It has been investigated for a long time by many authors to mimic the vision pro-cess.The most important step is to synthesize pigments having similar function ofrhodopsin,for example,to combine ll-cis-retinal with op...It has been investigated for a long time by many authors to mimic the vision pro-cess.The most important step is to synthesize pigments having similar function ofrhodopsin,for example,to combine ll-cis-retinal with opsin to form rhodopsin.Sinceit is difficult to obtain the ll-cis-retinal,Hubbard et al.suggested an“isorhodopsin”from9-cis-retinal and amine to mimic the rhodopsin,and a photoisomerization effect can be ob-served in this system.However,there were no reports about the photoelectric response ofthis“isorhodopsin”.In this article,we measure the photoresponse of展开更多
Ammonium toxicity in plants remains poorly understood despite extensive research.While nitrate is known to benefit plant growth,the synergistic effects of nitrate in mitigating ammonium toxicity,even at low concentrat...Ammonium toxicity in plants remains poorly understood despite extensive research.While nitrate is known to benefit plant growth,the synergistic effects of nitrate in mitigating ammonium toxicity,even at low concentrations,are not fully elucidated.This review delves into the physiological and molecular nature of this phenomenon.To date,nitrate-dependent alleviation of ammonium toxicity is the result of cumulative consequences of the role of nitrate as a nutrient and signal in plant performance.The ability to counteract the ammonium-induced acidification through nitrate uptake and metabolism,the enhancement of potassium uptake as an essential nitrate counterion,and the nitratedependent signaling of key factors involved in ammonium assimilation,ROS scavenging,and growth hormone biosynthesis,are the most relevant hallmarks.In addition,evidence suggests that the availability of nitrate and ammonium has driven ecological selection in plants,determining current N preferences,and may have led to the selection of nitrate-dependent and ammonium-sensitive domesticated crops and the inefficient use of N fertilizers in agriculture.As ammonium toxicity limits N fertilization options and reduces agricultural yields,when it could be a more sustainable and cheaper alternative to nitrate,this review provides a better understanding of how plants use nitrate to counteract the problematic aspects of ammonium nutrition.展开更多
We investigated the polaron-assisted nonadiabatic dynamics in protonated TiO_(2),as well as the polaron-H_(2)O coupling and its effects on the relaxation of photogenerated electrons.We observed that different polaron ...We investigated the polaron-assisted nonadiabatic dynamics in protonated TiO_(2),as well as the polaron-H_(2)O coupling and its effects on the relaxation of photogenerated electrons.We observed that different polaron hopping regimes result in varied nonadiabatic couplings and relaxations of excited electrons from the conduction band minimum to the gap states of protonated TiO_(2),with a weak dependence on the actual trapping site of the polaron.Surface-adsorbed H_(2)O molecules can attract polarons toward the adsorbed Ti sites,with the coupling between H_(2)O and the polaron being inversely proportional to their distance.Our findings suggest that the lifetime of the photogenerated charge carriers can be extended by reducing the polaron-H_(2)O distances,with expected benefits to the efficiency of the reduced TiO 2 samples for photocatalytic applications.展开更多
This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-a...This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-assisted junction termination extension(RA-JTE),multiple floating zone JTE(MFZ-JTE),and field limiting rings(FLR)were fabricated and irradiated with45 Me V protons at fluences ranging from 1×10^(12) to 1×10^(14) cm^(-2).Experimental results,supported by TCAD simulations,show that the RA-JTE structure maintained stable breakdown performance with less than 1%variation due to its effective electric field redistribution by multiple P+rings.In contrast,MFZ-JTE and FLR exhibit breakdown voltage shifts of 6.1%and 15.2%,respectively,under the highest fluence.These results demonstrate the superior radiation tolerance of the RA-JTE structure under TID conditions and provide practical design guidance for radiation-hardened Si C power devices in space and other highradiation environments.展开更多
3D printing,as a versatile additive manufacturing technique,offers high design flexibility,rapid prototyping,minimal material waste,and the capability to fabricate complex,customized geometries.These attributes make i...3D printing,as a versatile additive manufacturing technique,offers high design flexibility,rapid prototyping,minimal material waste,and the capability to fabricate complex,customized geometries.These attributes make it particularly well-suited for low-temperature hydrogen electrochemical conversion devices—specifically,proton exchange membrane fuel cells,proton exchange membrane electrolyzer cells,anion exchange membrane electrolyzer cells,and alkaline electrolyzers—which demand finely structured components such as catalyst layers,gas diffusion layers,electrodes,porous transport layers,and bipolar plates.This review provides a focused and critical summary of the current progress in applying 3D printing technologies to these key components.It begins with a concise introduction to the principles and classifications of mainstream 3D printing methods relevant to the hydrogen energy sector and proceeds to analyze their specific applications and performance impacts across different device architectures.Finally,the review identifies existing technical challenges and outlines future research directions to accelerate the integration of 3D printing in nextgeneration low-temperature hydrogen energy systems.展开更多
Protonic ceramic fuel cells(PCFCs)have been recognized as promising power generation devices for future clean energy systems,owing to their relatively low activation energy for proton migration and high energy convers...Protonic ceramic fuel cells(PCFCs)have been recognized as promising power generation devices for future clean energy systems,owing to their relatively low activation energy for proton migration and high energy conversion efficiency.In certain application scenarios,the use of N_(2)O(a potent greenhouse gas),as an alternative oxidant to air,presents a feasible strategy.Herein,we report for the first time the operation of PCFCs employing N_(2)O as the oxidant.A hybrid Pr_(2)Ni_(0.6)Co_(0.4)O_(4-δ)(PNCO-214)catalyst is developed,comprising Ruddlesden-Popper(R-P)structured Pr_(4)Ni_(1.8)Co_(1.2)O_(10-δ)(PNCO-4310)and fluorite structured Pr_(6)O_(11)(PO-611),which synergistically exhibits exceptional catalytic activity toward both N_(2)O decomposition and the oxygen reduction reaction,achieving a conversion over 92% and an area specific resistance of 1.301Ω·cm^(2) at 600℃.Quasi-insitu temperature-dependent Fourier transform infrared(FTIR)and electrochemical impedance spectroscopy analyses reveal that abundant oxygen vacancies in PNCO-214 facilitate rapid adsorption and dissociation of N_(2)O into N_(2) and O_(2),while also promoting the surface exchange kinetics of proton/oxygen during oxygen reduction reaction(ORR).When applied in an anode-supported single cell with PNCO-214 cathode operating under N_(2)O,outstanding power density and low resistance are achieved,delivering 0.801 W·cm^(-2) and 0.245Ω·cm^(2) at 600℃.Satisfactory performance is also maintained even when the temperature is reduced to 500℃.Furthermore,the single cell demonstrates relatively good stability with negligible degradation over 130 h at 600℃ and 0.7 V.These findings underscore the potential of PNCO-214 as a highly effective cathode catalyst for enabling the use of N_(2)O as a viable oxidant in PCFCs for specific industrial applications.展开更多
The faradaic ion transfer of protonated 1,10-phenanthrolino [H(Phen)^+] across the interface between unbuffered aqueous and 1,2-dichloroethane(DCE)solutions was inves- tigated by means of current scan polarography at ...The faradaic ion transfer of protonated 1,10-phenanthrolino [H(Phen)^+] across the interface between unbuffered aqueous and 1,2-dichloroethane(DCE)solutions was inves- tigated by means of current scan polarography at ascending aqueous electrolyte electrode, as well as chronopotentiometry.It follows from the splitting of the waves observed at the pH of aqueous phase(sodium sulfate solution)between 2.5—3.8 that neutral reagent(Phen) distributes into the aqueous phase,where it is protonated.The positive wave is associated with the mass transfer controlled by the H^+ influx,whereas the negative one is by the Phen influx.The reverse chronopotentiometry indicated that all the protonated transfer processes were reversible.A good agreement between experimental results and theoretical treatment was achieved.The aqueous acid dissociation constant of protonated Phen,K_a,can be evalu- ated from the dependence of the wave heights on the pH in the base of the equilibrium.展开更多
The solid acid of the first protonated zincoborophosphate, (H 3O)Zn(H 2O) 2BP 2O 8·H 2O (1), was soventothermally synthesized by the reaction of Zn(NO 3) 2·6H 2O and H 3BO 3 with H 3PO 4 in a mi...The solid acid of the first protonated zincoborophosphate, (H 3O)Zn(H 2O) 2BP 2O 8·H 2O (1), was soventothermally synthesized by the reaction of Zn(NO 3) 2·6H 2O and H 3BO 3 with H 3PO 4 in a mixed solvent, and structurally characterized by single-crystal X-ray diffraction analysis. It crystallizes in the hexagonal P6 122, a=0.9604(4) nm, c=1.5297(6) nm, V=1.2218(8) nm 3, D c=2.921 g/cm 3, Z=6, F(000)=1080, μ=3.495 mm -1. The structure features that the tetrahedra-tetrahedra helices interconnected by octahedra and strong hydrogen bond interactions form a three-dimensional framework. The protonated water molecules are located at unique positions. Other characterizations by IR and thermal analysis are also described.展开更多
基金supported by the National Natural Science Foundation of China(No.2021YFC3200603)the Special Research Assistant Program,Chinese Academy of Sciences.
文摘Photocatalytic disinfection is an eco-friendly strategy for countering bacterial pollution in aquatic environments.Numerous strategies have been devised to facilitate the generation of reactive oxygen species(ROS)within photocatalysts,ultimately leading to the eradication of bacteria.However,the significance of the physical morphology of photocatalysts in the context of sterilization is frequently obscured,and the progress in the development of physical-chemical synergistic sterilization photocatalysts has been relatively limited.Herein,graphitic carbon nitride(g-C_(3)N_(4))is chemically protonated to expose more sharp edges.PL fluorescence and EIS results indicate that the protonation can accelerate photogenerated carrier separation and enhance ROS production.Meanwhile,the sharp edges on the protonated g-C_(3)N_(4)facilitate the physical disruption of cell walls for further promoting oxidative damage.Protonated C_(3)N_(4)demonstrated superior bactericidal performance than that of pristine g-C_(3)N_(4),effectively eliminating Escherichia coli within 40 minutes under irradiation.This work highlights the significance of incorporating physical and chemical synergies in photocatalyst design to enhance the disinfection efficiency of photocatalysis.
基金Funded by Natural Science Foundation of China (No. 50002007), Major Program of Chinese Education Ministry and Open Foundation of State Key Lab. of Advanced Tech. for Materials Syn-thesis and Processing.
文摘New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by EPMA, AAS, XRD, IR, DTA and so on. The structure may be described as treble perovskite sheets [Sr2Nb3O10]- interleaved with K+ ,H3O + or H+. These new compounds are new members of the Dion-Jacob-sonseries with n=3 for the general formula M[An-1 NbnO3n+1], and their indexed X-ray powder diffraction data were first reported in the paper.
基金Project supported by the National Basic Research Program of China (973 Program,Grant No.2013CB932804)the National Natural Science Foundation of China (Grant Nos.91227115 and 11121403)the Hundred Talent Program of the Chinese Academy of Sciences (CAS)
文摘Formation and dissociation mechanisms of C-C＋ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environment, a cytosine monomer is first protonated and then dimerized with an unprotonated cytosine monomer to form a C-C＋ base pair; in an alkaline environment, a protonated cytosine dimer is first unprotonated and then dissociated into two cytosine monomers. In addition, the force for detaching a C-C＋ base pair was found to be inversely proportional to the distance between the two cytosine monomers. These results provide a microscopic mechanism to qualitatively explain the experimentally observed reversible formation and dissociation of i-motifs.
基金supported in part by JSPS KAKENHI Grant Numbers in Japan(JP21H05229 to I.K.)JST CREST(JPMJCR21B2)The authors also thank Nobuko Yamaguchi for the financial support.
文摘Rhodopsin is a seven-helical transmembrane protein with a retinal chromophore covalently bound to a conserved lysine in helix G via a retinal protonated Schiff base(RPSB).Microbial rhodopsins absorb light through chromophore and play a fundamental role in optogenetics.Numerous microbial rhodopsins have been discovered,contributing to diverse functions and colors.Solid-state NMR spectroscopy has been instrumental in elucidating the conformation of chromophores and the three-dimensional structure of microbial rhodopsins.This review focuses on the 15N chemical shift values of RPSB and summarizes recent progress in the field.We displayed the correlation between the 15N isotropic chemical shift values of RPSB and the maximum absorption wavelength of rhodopsin using solid-state NMR spectroscopy.
文摘A modified method for preparation and purification of Schiff base and protonated Schiff base from 9-cis-retinal has been suggested. Reaction took place in chloroform phase and purification was conducted by using water to remove the excess solvent, base and acid.
文摘Converting sustainable solar energy into hydrogen energy over semiconductor-based photocatalytic materials provides an alternative to fossil fuel consumption.However,efficient photocatalytic splitting of water to realize carbon-free hydrogen production remains a challenge.Heterojunction photocatalysts with well-defined dimensionality and perfectly matched interfaces are promising for achieving highly efficient solar-to-hydrogen conversion.Herein,we report the fabrication of a novel type of protonated graphitic carbon nitride(PCN)/Ti3C2 MXene heterojunctions with strong interfacial interactions.As expected,the two-dimensional(2D)PCN/2D Ti3C2 MXene interface heterojunction achieves a highly improved hydrogen evolution rate(2181μmol∙g‒1)in comparison with bulk g-C3N4(393μmol∙g‒1)and protonated g-C3N4(816μmol∙g‒1).The charge-regulated surfaces of PCN and the accelerated charge transport at the face-to-face 2D/2D Schottky heterojunction interface are the major contributors to the excellent hydrogen evolution performance of the composite photocatalyst.
基金supported by the National Natural Science Foundation of China(Nos.21475065,21627801 and 11704280)
文摘Infrared multiple photon dissociation （IRMPD） spectroscopic and theoretical studies of protonated homodimers of amino acids generated by electrospray ionization in the gas phase have been reviewed. Results show that proton affinity （PA） may be applied as a probe to predict their structural type： salt- bridged or charge-solvated. Proline can be viewed as a reference. For an amino acid with a PA value higher than that of proline, the most stable conformation of its protonated homodimer tends to prefer salt- bridged conformation; otherwise, charge-solvated conformation is expected to be the most stable. However, side chain effects may cause the inaccuracy in structural determination due to the strong interactions with the charge, which makes the charge-solvated structure more stable even for species with high PA values. Temperature effect on distribution of different isomers is also very important. In lots of cases, the coexistence of multiple isomers is general, which makes the explanation of an overall IRMPD spectrum difficult. So a statistical view on the distribution of optimized isomers is very helpful.
文摘The low energy collisioninduced dissociation, linked scan techniques and isotopic labeling experiment were used to investigate the unimolecular fragmentation of protonated N-hydroxyphthalimide under electron impact and chemical ionization conditions. It was found that this compound shows an unusual reactivity towards protonation. Two possible sites of protonation have been proposed to explain the corresponding fragmentation processes, one is that the protonation takes place on the oxygen atom of hydroxyl group, resulting in the loss of water and the other is the formation of an intermediary protonbound complex in the fragmentation process, giving rise to the fragment ions of m/z 133 and m/z 135. The results show both cases are coexistence in the fragmentations of protonated N-hydroxyphthalimide, and the unimolecular fragmentation pathways are available.
基金Supported by the National Natural Science Foundation of China (21133007 and 20873105)the Ministry of Science and Technology (2011CB808504 and 2012CB214902)
文摘Density functional calculations are used to determine structural and electronic properties of P4,P4O6,P4O10,P20O30 and P20O50 clusters and their protonated derivatives.These oxygen-rich phosphorus oxides are predicted to have relatively high stabilities with respect to their components P4 and O2,and their unsaturated P and end-on O atoms as the proton acceptor can accommodate multiple protons to generate highly positively charged cationic clusters,such as P20O30H1010＋.Calculations indicate that P4O6 and P20O30 have higher reactivity toward the proton capture than the P4,P4O10 and P20O50 clusters,and the most stable protonated clusters among these different series of cationic clusters are P4H2……2＋,P4O6H2^2＋,P4O10H3^3＋,P20O30H4^4＋ and P20O50H4^4＋,respectively.The cage skeleton of the phosphorus oxide clusters shows high stability for the consecutive protonation,and the unsymmetrical stretching of the skeletal P-O bond and the wagging mode of P-H coupled with the P-O bond stretching have strong adsorptions.These computational findings are useful for further experimental and theoretical studies of novel phosphorus oxide clusters and their highly positively charged derivatives.
基金supported by the Science and Technology Project of Jiangsu Province(BZ2022056,BK20210356)the National Natural Science Foundation of China(22205109,21975128)the Fundamental Research Funds for the Central Universities(30922010812)。
文摘Covalent organic frameworks(COFs)are emerging as promising photocatalysts owing to their tailorable structures,exceptional crystallinity,and robustness.However,the photocatalytic performance of COFs is limited by fast charge recombination and inefficient charge migration.Herein,a novel post-synthetic partial protonation strategy is proposed to construct COFs with asymmetric unprotonated/protonated homojunctions,which endow them with an enlarged molecular dipole moment,thereby generating a strong built-in electric field that significantly enhances the charge separation and transport efficiencies in COFs.In addition,the protonation process extends the light absorption range and improves the hydrophilicity of COFs.The photocatalytic hydrogen evolution rate of the partially protonated TPE-COF and ETTBA-COF is enhanced by 88-and 175-fold relative to their pristine counterparts,4.3 and 2.48 times those of fully protonated counterparts,respectively.Our results clearly demonstrate the pivotal role of the asymmetric unprotonated/protonated homojunctions within COFs in the photocatalytic hydrogen evolution.This post-synthetic partial protonation strategy provides a novel paradigm for establishing internal electric fields within COFs.
文摘In this work, we demonstrated the successful construction of metal-free zero- dimensional/two-dimensional carbon nanodot （CND）-hybridized protonatedg=C3N4 （pCN） （CND/pCN） heterojunction photocatalysts b; means of electrostatic attraction. We experimentally found that CNDs with an average diameter of 4.4 nm were uniformly distributed on the surface of pCN using electron microscopy analysis. The CND/pCN-3 sample with a CND content of 3 wt.% showed thehighest catalytic activity in the CO2 photoreduction process under visible and simulated solar light. This process results in the evolution of CH4 and CO. Thetotal amounts of CH4 and CO generated by the CND/pCN-3 photocatalyst after 10 h of visible-light activity were found to be 29.23 and 58.82 molgcatalyst-1, respectively. These values were 3.6 and 2.28 times higher, respectively, than thearn＊ounts generated when using pCN alone. The corresponding apparent quantum efficiency （AQE） was calculated to be 0.076%. Furthermore, the CND/pCN-3 sample demonstrated high stability and durability after four consecutive photoreaction cycles, with no significant decrease in the catalytic activity.
基金Project supported by the National Natural Science Foundation of China.
文摘Ordered thin organic films deposited on solid substrates by the Langmuir-Blodgett(LB) technique have attracted much attention because of their possibility of being applied tofunctional molecular device architectures, such as electronic, nonlinear optical and bio-logical sensors. Very elegant work has been carried out by Kuhn and his
文摘It has been investigated for a long time by many authors to mimic the vision pro-cess.The most important step is to synthesize pigments having similar function ofrhodopsin,for example,to combine ll-cis-retinal with opsin to form rhodopsin.Sinceit is difficult to obtain the ll-cis-retinal,Hubbard et al.suggested an“isorhodopsin”from9-cis-retinal and amine to mimic the rhodopsin,and a photoisomerization effect can be ob-served in this system.However,there were no reports about the photoelectric response ofthis“isorhodopsin”.In this article,we measure the photoresponse of
基金supported by an MCIN RyC Programme MCIN/AEI/10.13039/501100011033the‘European Union Next Generation EU/PRTR’under grant no.RYC2021-032345-I+1 种基金supported by the AEI(grant no.PID2019-107463RJ-I00/AEI/10.13039/501100011033)the Regional Research and Development Programme of the Government of Navarre(call 2019,project NitroHealthy,PC068).
文摘Ammonium toxicity in plants remains poorly understood despite extensive research.While nitrate is known to benefit plant growth,the synergistic effects of nitrate in mitigating ammonium toxicity,even at low concentrations,are not fully elucidated.This review delves into the physiological and molecular nature of this phenomenon.To date,nitrate-dependent alleviation of ammonium toxicity is the result of cumulative consequences of the role of nitrate as a nutrient and signal in plant performance.The ability to counteract the ammonium-induced acidification through nitrate uptake and metabolism,the enhancement of potassium uptake as an essential nitrate counterion,and the nitratedependent signaling of key factors involved in ammonium assimilation,ROS scavenging,and growth hormone biosynthesis,are the most relevant hallmarks.In addition,evidence suggests that the availability of nitrate and ammonium has driven ecological selection in plants,determining current N preferences,and may have led to the selection of nitrate-dependent and ammonium-sensitive domesticated crops and the inefficient use of N fertilizers in agriculture.As ammonium toxicity limits N fertilization options and reduces agricultural yields,when it could be a more sustainable and cheaper alternative to nitrate,this review provides a better understanding of how plants use nitrate to counteract the problematic aspects of ammonium nutrition.
基金This study was financially supported by the National Science Fund for Distinguished Young Scholars(No.52225308)the National Natural Science Foundation of China(Nos.11974037,12204168,and 12104515)L.M.L.and G.T.acknowledge support from the Royal Soci-ety Newton Advanced Fellowship scheme(grant No.NAF\R1\180242)。
文摘We investigated the polaron-assisted nonadiabatic dynamics in protonated TiO_(2),as well as the polaron-H_(2)O coupling and its effects on the relaxation of photogenerated electrons.We observed that different polaron hopping regimes result in varied nonadiabatic couplings and relaxations of excited electrons from the conduction band minimum to the gap states of protonated TiO_(2),with a weak dependence on the actual trapping site of the polaron.Surface-adsorbed H_(2)O molecules can attract polarons toward the adsorbed Ti sites,with the coupling between H_(2)O and the polaron being inversely proportional to their distance.Our findings suggest that the lifetime of the photogenerated charge carriers can be extended by reducing the polaron-H_(2)O distances,with expected benefits to the efficiency of the reduced TiO 2 samples for photocatalytic applications.
基金supported by the IITP(Institute for Information&Communications Technology Planning&Evaluation)under the ITRC(Information Technology Research Center)support program(IITP-2025-RS-2024-00438288)grant funded by the Korea government(MSIT)+1 种基金National Research Council of Science&Technology(NST)grant by the MSIT(Aerospace Semiconductor Strategy Research Project No.GTL25051-000)supported by the IC Design Education Center(IDEC),Korea。
文摘This work presents a systematic analysis of proton-induced total ionizing dose(TID)effects in 1.2 k V silicon carbide(SiC)power devices with various edge termination structures.Three edge terminations including ring-assisted junction termination extension(RA-JTE),multiple floating zone JTE(MFZ-JTE),and field limiting rings(FLR)were fabricated and irradiated with45 Me V protons at fluences ranging from 1×10^(12) to 1×10^(14) cm^(-2).Experimental results,supported by TCAD simulations,show that the RA-JTE structure maintained stable breakdown performance with less than 1%variation due to its effective electric field redistribution by multiple P+rings.In contrast,MFZ-JTE and FLR exhibit breakdown voltage shifts of 6.1%and 15.2%,respectively,under the highest fluence.These results demonstrate the superior radiation tolerance of the RA-JTE structure under TID conditions and provide practical design guidance for radiation-hardened Si C power devices in space and other highradiation environments.
基金the support from the National Natural Science Foundation of China(Nos.22208376,UA22A20429)the Qingdao New Energy Shandong Laboratory Open Project(QNESL OP 202303)+3 种基金Shandong Provincial Natural Science Foundation(Nos.ZR2024QB175,ZR2023LFG005)Fundamental Research Funds for the Central Universities(No.25CX07002A)National Natural Science Foundation of China(Z202401390008)The Hunan Provincial Natural Science Foundation(2025JJ60301)。
文摘3D printing,as a versatile additive manufacturing technique,offers high design flexibility,rapid prototyping,minimal material waste,and the capability to fabricate complex,customized geometries.These attributes make it particularly well-suited for low-temperature hydrogen electrochemical conversion devices—specifically,proton exchange membrane fuel cells,proton exchange membrane electrolyzer cells,anion exchange membrane electrolyzer cells,and alkaline electrolyzers—which demand finely structured components such as catalyst layers,gas diffusion layers,electrodes,porous transport layers,and bipolar plates.This review provides a focused and critical summary of the current progress in applying 3D printing technologies to these key components.It begins with a concise introduction to the principles and classifications of mainstream 3D printing methods relevant to the hydrogen energy sector and proceeds to analyze their specific applications and performance impacts across different device architectures.Finally,the review identifies existing technical challenges and outlines future research directions to accelerate the integration of 3D printing in nextgeneration low-temperature hydrogen energy systems.
基金financially supported by the National Key R&D Program of China(No.2024YFF0506300)National Natural Science Foundation of China(No.52336009)+5 种基金Key Research and Development Program of Shaanxi(No.2024CY2-GJHX-66)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515010429)Natural Science Basic Research Plan in Shaanxi Province of China(No.2024JC-YBQN-0475)Xidian University Specially Funded Project for Interdisciplinary Exploration(No.TZJH2024063)the Fundamental Research Funds for the Central Universities(No.QTZX23061)the Innovation Center of Nuclear Power Technology(No.HDLCXZX-2022-ZH-013).
文摘Protonic ceramic fuel cells(PCFCs)have been recognized as promising power generation devices for future clean energy systems,owing to their relatively low activation energy for proton migration and high energy conversion efficiency.In certain application scenarios,the use of N_(2)O(a potent greenhouse gas),as an alternative oxidant to air,presents a feasible strategy.Herein,we report for the first time the operation of PCFCs employing N_(2)O as the oxidant.A hybrid Pr_(2)Ni_(0.6)Co_(0.4)O_(4-δ)(PNCO-214)catalyst is developed,comprising Ruddlesden-Popper(R-P)structured Pr_(4)Ni_(1.8)Co_(1.2)O_(10-δ)(PNCO-4310)and fluorite structured Pr_(6)O_(11)(PO-611),which synergistically exhibits exceptional catalytic activity toward both N_(2)O decomposition and the oxygen reduction reaction,achieving a conversion over 92% and an area specific resistance of 1.301Ω·cm^(2) at 600℃.Quasi-insitu temperature-dependent Fourier transform infrared(FTIR)and electrochemical impedance spectroscopy analyses reveal that abundant oxygen vacancies in PNCO-214 facilitate rapid adsorption and dissociation of N_(2)O into N_(2) and O_(2),while also promoting the surface exchange kinetics of proton/oxygen during oxygen reduction reaction(ORR).When applied in an anode-supported single cell with PNCO-214 cathode operating under N_(2)O,outstanding power density and low resistance are achieved,delivering 0.801 W·cm^(-2) and 0.245Ω·cm^(2) at 600℃.Satisfactory performance is also maintained even when the temperature is reduced to 500℃.Furthermore,the single cell demonstrates relatively good stability with negligible degradation over 130 h at 600℃ and 0.7 V.These findings underscore the potential of PNCO-214 as a highly effective cathode catalyst for enabling the use of N_(2)O as a viable oxidant in PCFCs for specific industrial applications.
基金Project supported by the National Natural Science Foundation of China.
文摘The faradaic ion transfer of protonated 1,10-phenanthrolino [H(Phen)^+] across the interface between unbuffered aqueous and 1,2-dichloroethane(DCE)solutions was inves- tigated by means of current scan polarography at ascending aqueous electrolyte electrode, as well as chronopotentiometry.It follows from the splitting of the waves observed at the pH of aqueous phase(sodium sulfate solution)between 2.5—3.8 that neutral reagent(Phen) distributes into the aqueous phase,where it is protonated.The positive wave is associated with the mass transfer controlled by the H^+ influx,whereas the negative one is by the Phen influx.The reverse chronopotentiometry indicated that all the protonated transfer processes were reversible.A good agreement between experimental results and theoretical treatment was achieved.The aqueous acid dissociation constant of protonated Phen,K_a,can be evalu- ated from the dependence of the wave heights on the pH in the base of the equilibrium.
文摘The solid acid of the first protonated zincoborophosphate, (H 3O)Zn(H 2O) 2BP 2O 8·H 2O (1), was soventothermally synthesized by the reaction of Zn(NO 3) 2·6H 2O and H 3BO 3 with H 3PO 4 in a mixed solvent, and structurally characterized by single-crystal X-ray diffraction analysis. It crystallizes in the hexagonal P6 122, a=0.9604(4) nm, c=1.5297(6) nm, V=1.2218(8) nm 3, D c=2.921 g/cm 3, Z=6, F(000)=1080, μ=3.495 mm -1. The structure features that the tetrahedra-tetrahedra helices interconnected by octahedra and strong hydrogen bond interactions form a three-dimensional framework. The protonated water molecules are located at unique positions. Other characterizations by IR and thermal analysis are also described.
