Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process.Interestingly,in this work,an innovative approach was employed to augmen...Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process.Interestingly,in this work,an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst(Pd/SiO_(2))by adding alkali metal potassium(K).A formidable promotion effect was observed when the K doping to Pd/SiO_(2) catalysts.It achieves a conversion rate of 93%for 270 ppmV of HCHO to harmless CO_(2) and H_(2)O at a weight hourly space velocity(WHSV)of 300,000 mL/(g·hr)at 25℃.Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition,which not only stabilized Pd species on the carrier surface but alsomarkedly enhanced its dispersal on the SiO_(2) carrier.The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO_(2) catalysts.The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover,which also contributed to elevating the electron density on the Pd sites.Meanwhile,the oxygen vacancies favored the O_(2) activation to formmore reactive oxygen species participating in the HCHO oxidation reaction,thus improving the performance of Pd/SiO_(2) catalysts displayed for HCHO oxidation.This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.展开更多
Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） ...Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） at room temperature under high GHSV of 600000 ml/（g＆#183;s）. Au/γ‐Al2O3 cata‐lyst showed distinctive catalytic performance, presenting the highest initial HCHO conversion and stability. Correlating the reaction rate with Au particle size, there is a linear relationship, suggesting that the smaller Au particle size with higher dispersion possesses high reactivity for HCHO oxida‐tion. All the catalysts deactivated at high GHSV （600000 ml/（g＆#183;s））, but in a quite different rate. Re‐ducible oxide （CeO2 and FeOx） could stabilize gold through O linkage and therefore exhibits a better stability for HCHO oxidation reaction. However, the aggregation of gold particles occurred over Au/SiO2 and Au/HZSM‐5 catalysts, which result in the fast deactivation. Therefore, our results sug‐gest that the reducibility of the supports for Au catalysis has no direct influence on the activity, but affects the catalytic stability.展开更多
The complete catalytic oxidation of formaldehyde (HCHO) to CO_(2)and H_(2)O at room temperature is a green route for indoor HCHO removal.Zeolite is an excellent carrier material for HCHO oxidation due to its large sur...The complete catalytic oxidation of formaldehyde (HCHO) to CO_(2)and H_(2)O at room temperature is a green route for indoor HCHO removal.Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area,intricate pores and high adsorption capacity.However,the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature.In this work,we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation.Activity tests illustrated that HCHO could be completely oxidized to CO_(2)and H_(2)O at a nearly 100%conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g·hr) at 25℃,when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L.The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction.The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene(DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.展开更多
The strong metal-support interaction(SMSI)plays a pivotal role in regulating electronic properties and activating surface oxygen species.In this work,we report light-irradiation-modulated SMSI for enhanced formaldehyd...The strong metal-support interaction(SMSI)plays a pivotal role in regulating electronic properties and activating surface oxygen species.In this work,we report light-irradiation-modulated SMSI for enhanced formaldehyde(HCHO)oxidation.Specifically,the SMSI between Pt nanoparticles(NPs)and Bi_(2)MoO_(6)cre-ated surface-active oxygen at Pt-Bi_(2)MoO_(6)interfaces to activate HCHO to dioxymethylene(DOM).Notably,light irradiation boosted the SMSI and catalytic activity.Moreover,photogenerated holes in Bi_(2)MoO 6 im-proved HCHO adsorption and activation,while photogenerated electrons migrated from Bi_(2)MoO_(6)to Pt NPs to promote O_(2)adsorption and activation,accelerating the oxidation of DOM to CO_(2)and H_(2)O.The light-modulated SMSI and the synergy between photocatalysis and thermocatalysis lead to enhanced cat-alytic oxidation activity,providing a practical strategy for indoor volatile organic compound(VOC)de-composition under ambient conditions.展开更多
Formate can be synthesized electrochemically by CO_(2) reduction reaction(CO_(2)RR)or formalde-hyde oxidation reaction(FOR).The CO_(2)RR approach suffers from kinetic-sluggish oxygen evolution reac-tion at the anode.T...Formate can be synthesized electrochemically by CO_(2) reduction reaction(CO_(2)RR)or formalde-hyde oxidation reaction(FOR).The CO_(2)RR approach suffers from kinetic-sluggish oxygen evolution reac-tion at the anode.To this end,an electrochemical sys-tem combining cathodic CO_(2)RR with anodic FOR was developed,which enables the formate electrosynthesis at ultra-low voltage.Cathodic CO_(2)RR employing the BiOCl electrode in H-cell exhibited formate Faradaic efficiency(FE)higher than 90% within a wide potential range from−0.48 to−1.32 V_(RHE).In flow cell,the current density of 100 mA cm^(−2) was achieved at−0.67 V_(RHE).The anodic FOR using the Cu_(2)O electrode displayed a low onset potential of−0.13 V_(RHE) and nearly 100%formate and H_(2) selectivity from 0.05 to 0.35 V_(RHE).The CO_(2)RR and FOR were constructed in a flow cell through membrane electrode assembly for the electrosynthesis of formate,where the CO_(2)RR//FOR delivered an enhanced current density of 100 mA cm^(−2) at 0.86 V.This work provides a promising pair-electrosynthesis of value-added chemicals with high FE and low energy consumption.展开更多
We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 nanosheets.The Au nanoparticles were stabilized by structural defec...We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 nanosheets.The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet,including crystal steps and edges,thereby fixing the Au-TiO2 perimeter interface.Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface.The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface.Such vacancies are essential for generating active oxygen species（-＊O^-） on the TiO2 surface and Ti^3＋ ions in bulk TiO2.These ions can then form Ti^3＋-O^--Ti^4＋species,which are known to enhance the catalytic activity of formaldehyde（HCHO） oxidation.These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials.展开更多
A series of α-MnO_(2) catalysts with various Mn valence states were treated by hydrogen reduction for different periods of time. Their catalytic capacity for formaldehyde(HCHO) oxidation was evaluated. The results in...A series of α-MnO_(2) catalysts with various Mn valence states were treated by hydrogen reduction for different periods of time. Their catalytic capacity for formaldehyde(HCHO) oxidation was evaluated. The results indicated that hydrogen reduction dramatically improves the catalytic performance of α-MnO_(2) in HCHO oxidation. The α-MnO_(2) sample reduced by hydrogen for 2 h possessed superior activity and could completely oxidize 150 ppm HCHO to CO_(2) and H_(2)O at 70℃. Multiple characterization results illustrated that hydrogen reduction contributed to the production of more oxygen vacancies. The oxygen vacancies on the catalyst surface enhanced the adsorption, activation and mobility of O_(2) molecules, and thereby enhanced HCHO catalytic oxidation. This study provides novel insight into the design of outstanding MnO_x catalysts for HCHO oxidation at low temperature.展开更多
Flower-like tin oxide-supported platinum（Pt/SnOx） with a hierarchical structure was synthesized by a hydrothermal method and characterized by XRD,SEM,TEM,high resolution TEM,XPS and nitrogen adsorption.The flower-li...Flower-like tin oxide-supported platinum（Pt/SnOx） with a hierarchical structure was synthesized by a hydrothermal method and characterized by XRD,SEM,TEM,high resolution TEM,XPS and nitrogen adsorption.The flower-like Pt/SnOx microspheres of 1 μm in diameter were composed of staggered petal-like nanosheets with a thickness of 20 nm.Pt nanoparticles（NPs） of 2-3 nm were well dispersed on the SnOx nanosheets.The catalyst was tested in the catalytic oxidation of gaseous formaldehyde（HCHO） at room temperature,and exhibited enhanced activity compared to Pt NPs supported on commercial SnO and ground SnOx.HCHO removal of 87%was achieved over the hierarchical Pt/SnOx after 1 h of reaction,which was 1.5 times that over the ground SnOx-supported Pt（Pt/g-SnOx）,and the high activity was maintained after six recycles,showing the high stability of this catalyst.HCHO decomposition kinetics was modeled as a second order reaction.The reaction rate constant for Pt/SnOx was 5.6 times higher than Pt/g-SnOx.The hierarchical pore structure was beneficial for the diffusion and adsorption of HCHO molecules,and the highly dispersed Pt NPs on the SnOx nanosheets were the active sites for the oxidative decomposition of HCHO into CO2 and H2O.This study provided a promising approach for designing efficient catalysts for indoor HCHO removal at ambient temperature.展开更多
Through the impregnation method, Ag catalysts with different support (such as TiO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub>) were prepared and then tested for catalytic oxidati...Through the impregnation method, Ag catalysts with different support (such as TiO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub>) were prepared and then tested for catalytic oxidation of formaldehyde (HCHO) at low temperatures. The Ag/TiO<sub>2</sub> catalyst exhibited strong catalytic performance, converting HCHO to CO<sub>2</sub> and H<sub>2</sub>O at around 95°C. However, the Ag/Al<sub>2</sub>O<sub>3</sub> catalysts showed much lower activity and reached 100% conversion at 125°C. The Ag-based catalysts were next characterized by several methods (XRD, TEM, FT-R, BET and H<sub>2</sub>-TPR). Results of characterization revealed that support dramatically impacts the size and dispersion of Ag particles. The XRD analysis showed the existence of different peaks of the silver on the surface of Al<sub>2</sub>O<sub>3</sub> in the contrast with TiO<sub>2</sub> no specific peaks exist. Therefore, the size of the Ag particles and their dispersion are the most important factors that affect their catalytic performance for formaldehyde oxidation. In terms of catalytic performance for HCHO oxidation, the Ag/TiO<sub>2 </sub>catalyst possesses the best Ag dispersion, as well as the smallest Ag particle size.展开更多
The formaldehyde oxidation reaction(FOR)on a Cu-based electrocatalyst enables hydrogen(H_(2))at the anode in OH−solution,facilitating a bipolar H_(2) production system at ultra-low electrolysis voltage.However,the spe...The formaldehyde oxidation reaction(FOR)on a Cu-based electrocatalyst enables hydrogen(H_(2))at the anode in OH−solution,facilitating a bipolar H_(2) production system at ultra-low electrolysis voltage.However,the specific impact of*OH adsorption on the Cu surface regarding the FOR has been rarely investigated.Herein,the strong*OH adsorption Cu(S-OH Cu)electrode,which exhibits high activity and excellent stability of FOR,is developed to investigate the specific impact of*OH adsorption on the Cu surface during the FOR process.Impressively,the increased*OH adsorption on the Cu electrode,typically regarded as a poisoning effect that diminishes inherent FOR activity by reducing the adsorption of intermediate reactants,is firstly revealed as an OH-induced favorable reconstruction effect that significantly improves FOR stability.Specifically,the dual functions of OH-induced favoring reconstruction include accelerating the phase transition of the Cu(0)/Cu(I)redox cycle to refresh the active site and optimizing surface reconstruction to preferentially generate Cu(220)with stronger adsorption energy for H_(2)C(OH)O*and lower C−H barrier energy during FOR.This work provides a promising strategy for designing stable Cu electrocatalysts for FOR to produce hydrogen with extremely low energy input.展开更多
Co3O4 catalysts prepared with different precipitants（NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3）were investigated for the oxidation of formaldehyde（HCHO）.Among these,KHCO3-precipitated Co3O4（KHCO3-Co） was the most...Co3O4 catalysts prepared with different precipitants（NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3）were investigated for the oxidation of formaldehyde（HCHO）.Among these,KHCO3-precipitated Co3O4（KHCO3-Co） was the most active low-temperature catalyst,and was able to completely oxidize HCHO at the 100-ppm level to CO2 at 90℃.In situ diffuse reflectance infrared spectroscopy demonstrated that hydroxyl groups on the catalyst surface were regenerated by K~＋ and CO3^（2-）,thus promoting the oxidation of HCHO.Moreover,H2-temperature programmed reduction and X-ray photoelectron spectroscopy showed that employing KHCO3 as the precipitant increased the Co^3＋/Co^2＋molar ratio on the surface of the Co3O4 catalyst,thus further promoting oxidation.Structural characterization revealed that catalysts precipitated with carbonate or bicarbonate reagents exhibited greater specific surface areas and pore volumes.Overall,these data suggest that the high activity observed during the Co3O4 catalyzed oxidation of HCHO can be primarily attributed to the presence of K~＋ and CO3^（2-） on the Co3O4 surface and the favorable Co^3＋/Co^2＋ ratio.展开更多
Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO o...Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO oxidation,yet suffer from low metal utilization.Efforts focus on designing catalysts with enhanced intrinsic activity and reduced noble metal loading.In this study,we developed a simple pretreatment method using ammonia solution on SiO_(2)carrier to enhance the activity of the Pd/SiO_(2)catalyst for HCHO oxidation.After the carrier was pretreated with an ammonia solution,a significant promoting effect was observed on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst.It achieved almost complete oxidation of 150 ppmV of HCHO at 25℃,much better than the Pd/SiO_(2)-R(5%HCHO conversion rate).Multiple characterization results indicated that the ammonia solution pretreatment of the SiO_(2)carrier increased the surface defects,facilitating the anchoring of Pd nanoparticles and increasing their dispersion.The increase dispersion of Pd resulted in the generation of additional oxygen vacancies on the catalyst surfaces.The increased in oxygen vacancies on the catalyst was beneficial for enhancing the catalyst's ability to activate H_(2)O to form surface hydroxyl groups,thereby accelerating the catalytic oxidation process of HCHO.The reaction mechanism of HCHO on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst mainly follows an efficient pathway:firstly,the HCHO being oxidized by surface active hydroxyl groups to formate;subsequently,the formate being oxidized by hydroxyl groups to H_(2)O and CO_(2).This study provides a promising strategy for designing high-performance noble metal catalysts for HCHO catalytic oxidation.展开更多
Flaky and nanospherical birnessite and birnessite-supported Pt catalysts were successfully prepared and characterized by means of Xray diffraction （XRD）,transmission electron microscopy （TEM）,energy dispersive spe...Flaky and nanospherical birnessite and birnessite-supported Pt catalysts were successfully prepared and characterized by means of Xray diffraction （XRD）,transmission electron microscopy （TEM）,energy dispersive spectroscopy （EDS） and N2 adsorption-desorption.Effects of the birnessite morphology and Pt reduction method on the catalytic activity for the complete oxidation of formaldehyde （HCHO） were investigated.It was found that flaky birnessite exhibited higher catalytic activity than nanospherical birnessite.The promoting effect of Pt on the birnessite catalyst indicated that the reduction method of the Pt precursor greatly influenced the catalytic performance.Flaky birnessite-supported Pt nanoparticles reduced by KBH 4 showed the highest catalytic activity and could completely oxidize HCHO into CO2 and H2O at 50℃,whereas the sample reduced using H2-plasma showed lower activity for HCHO oxidation.The differences in catalytic activity of these materials were jointly attributed to the effects of pore structure,surface active sites exposed to HCHO and the dispersion of Pt nanoparticles.展开更多
MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samp...MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samples： coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO2 are the main factor affecting the catalytic activities of these samples, and γ- MnO2 shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO2. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO2. We also studied intermediate species. The dioxymethylene （DOM） and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO2. A proposed mechanism of formaldehyde oxidation over Au/MnO2 catalysts was also obtained.展开更多
A series of CeO2-Co3O4 mixed oxide catalysts with different Co/（Co＋Ce） atomic ratios were synthesized by citric acid sol-gel method and used for catalytic oxidation of formaldehyde（HCHO）. Many techniques such as ...A series of CeO2-Co3O4 mixed oxide catalysts with different Co/（Co＋Ce） atomic ratios were synthesized by citric acid sol-gel method and used for catalytic oxidation of formaldehyde（HCHO）. Many techniques such as Brumauer-Emmett-Teller（BET）, X-ray diffraction（XRD）, scanning electron microscopy（FE-SEM）, temperature programmed reduction（H_2-TPR）, temperature-programmed desorption（O_2-TPD） and X-ray photoelectron spectroscopy（XPS） were used to characterize catalysts. The results of catalytic performance tests showed that the catalyst CeO_2-Co_3O_4 with Co/（Co＋Ce） ratio of 0.95 exhibited the best performance, and the temperature of complete oxidation of HCHO was 80 oC. The analytical results indicated that the addition of CeO_2 enhanced the specific surface area of Co_3O_4 and the fine dispersion of both of them. Moreover, the strong interaction between CeO_2 and Co_3O_4 resulted in the unique redox properties, which enhanced the available surface active oxygen and led to high valence state of cobalt oxide species. All those effects played crucial roles in the excellent performance of CeO_2-Co_3O_4 for the HCHO oxidation.展开更多
Formaldehyde oxidation reaction(FOR)is a promising reaction alternative to the anodic oxygen evolution reaction(OER)owing to its ultra-low electrolysis potential and ability to produce formate and hydrogen gas.In this...Formaldehyde oxidation reaction(FOR)is a promising reaction alternative to the anodic oxygen evolution reaction(OER)owing to its ultra-low electrolysis potential and ability to produce formate and hydrogen gas.In this work,the electrode for FOR is prepared using Ag/Ag_(2)O nanoparticles(Ag/Ag_(2)O NPs)covered with Nafion membrane as the catalysts modified onto nickel foam(NF).Ag/Ag_(2)O NPs@NF exhibits significantly higher FOR activity than Ag NPs@NF and Ag_(2)O NPs@NF.At 100 mA·cm^(-2),the FOR potential on the Ag/Ag_(2)O NPs@NF electrode is only 0.16 V(vs.RHE).Meanwhile,the Faradaic efficiencies can reach up to 100% for both formate and H_(2) produced by FOR.Density functional theory(DFT)calculations indicate that the Ag/Ag_(2)O heterostructure exhibits lower reaction energy barriers for generating formate and H2 than pure Ag and Ag_(2)O.This work introduces a new synthetic approach for developing novel FOR catalysts and offers insights into the potential application prospects of FOR.展开更多
Replacing the oxygen evolution reaction(OER)with the anodic formaldehyde oxidation reaction(FOR)is crucial for achieving low-voltage dual-electrode hydrogen evolution.However,existing FOR catalysts face challenges suc...Replacing the oxygen evolution reaction(OER)with the anodic formaldehyde oxidation reaction(FOR)is crucial for achieving low-voltage dual-electrode hydrogen evolution.However,existing FOR catalysts face challenges such as low activity,high transition state barriers,and unclear reaction mechanisms.In this study,a three-dimensional nano-composite Cu_(2)O/Cu/Mn_(2)O_(3)heterogeneous catalyst with enhanced hydrogen spillover effect was synthesized through hydrothermal and photosensitive oxidation treatment techniques.The catalyst consists of~20 nm Cu_(2)O/Cu and 30-70 nm Mn_(2)O_(3)nanoparticles.The hydrogen spillover effect enhanced Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst demonstrated outstanding FOR performance,with an anode potential of only 0.128 V at a current density of 100 mA cm^(-2),significantly lower than that of the Cu_(2)O/Cu-CC catalyst(0.25 V)and the OER potential(1.726 V).Moreover,the Faraday efficiency of the Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst reached~100%.The electrocatalyst’s FOR performance remains stable over 50 h without decay,and its hydrogen evolution reaction(HER)performance surpasses that of Cu and MnOxelectrocatalysts.Density functional theory(DFT)calculations suggested that the Cu_(2)O/Cu/Mn_(2)O_(3)catalyst significantly lowers the energy barriers for C-H bond breaking(0.48 eV)and H-H bond formation(-0.99 eV)by promoting the hydrogen spillover effect.This study provides theoretical support for designing efficient and stable low-energy dual-electrode hydrogen evolution catalysts and validates their potential through experiments.展开更多
Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single a...Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.展开更多
Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterizat...Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.展开更多
Top‐down synthesis has been used to prepare catalytic materials with nanometer sizes,but fabricating atomically dispersed metal catalysts remains a challenge because surface single metal atoms are prone to aggregatio...Top‐down synthesis has been used to prepare catalytic materials with nanometer sizes,but fabricating atomically dispersed metal catalysts remains a challenge because surface single metal atoms are prone to aggregation or coalescence.A top‐down strategy is used to synthesize atomically dispersed metal catalysts,based on supported Ag nanoparticles.The changes of the geometric and electronic structures of the Ag atoms during the top‐down process are studied using the in situ synchrotron X‐ray diffraction technique,ex situ X‐ray absorption spectroscopy,and transmission electron microscopy.The experimental results,coupled with the density functional theory calculations,demonstrate that the electronic perturbation of the Ag frontier orbitals,induced by the Ag‐O interactions at the perimeter of the metal‐support interface,is the driving force of the top‐down process.The top‐down synthesis has two important functions:to increase the number of catalytic active sites and to facilitate the study of complex reaction mechanisms(e.g.,formaldehyde oxidation)by developing single‐site model catalysts.展开更多
基金supported by the Youth Innovation Promotion Association,CAS(No.2020310)Sanming University(No.23YG05).
文摘Highly dispersed noble metals are acknowledged for its pivotal role in influencing the efficiency of catalysts during the HCHO oxidation process.Interestingly,in this work,an innovative approach was employed to augmenting the stabilization of noble metals on irreducible carriers supported noble metal catalyst(Pd/SiO_(2))by adding alkali metal potassium(K).A formidable promotion effect was observed when the K doping to Pd/SiO_(2) catalysts.It achieves a conversion rate of 93%for 270 ppmV of HCHO to harmless CO_(2) and H_(2)O at a weight hourly space velocity(WHSV)of 300,000 mL/(g·hr)at 25℃.Multiple characterization results illustrated that a strong interaction between added K and Pd species was formed after K addition,which not only stabilized Pd species on the carrier surface but alsomarkedly enhanced its dispersal on the SiO_(2) carrier.The increasing Pd dispersion induced more oxygen vacancies on the surfaces of the Pd/SiO_(2) catalysts.The formation of these oxygen vacancies can be attributed to the phenomenon of hydrogen spillover,which also contributed to elevating the electron density on the Pd sites.Meanwhile,the oxygen vacancies favored the O_(2) activation to formmore reactive oxygen species participating in the HCHO oxidation reaction,thus improving the performance of Pd/SiO_(2) catalysts displayed for HCHO oxidation.This study provides a simple strategy to design high-performance irreducible carriers supported noble metal catalysts for HCHO catalytic oxidation.
基金supported by the National Natural Science Foundation of China(21373037,21577013)China Postdoctoral Science Foundation(2014M560201)the Fundamental Research Funds for the Central Universities(DUT15TD49,DUT16ZD224)~~
文摘Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） at room temperature under high GHSV of 600000 ml/（g＆#183;s）. Au/γ‐Al2O3 cata‐lyst showed distinctive catalytic performance, presenting the highest initial HCHO conversion and stability. Correlating the reaction rate with Au particle size, there is a linear relationship, suggesting that the smaller Au particle size with higher dispersion possesses high reactivity for HCHO oxida‐tion. All the catalysts deactivated at high GHSV （600000 ml/（g＆#183;s））, but in a quite different rate. Re‐ducible oxide （CeO2 and FeOx） could stabilize gold through O linkage and therefore exhibits a better stability for HCHO oxidation reaction. However, the aggregation of gold particles occurred over Au/SiO2 and Au/HZSM‐5 catalysts, which result in the fast deactivation. Therefore, our results sug‐gest that the reducibility of the supports for Au catalysis has no direct influence on the activity, but affects the catalytic stability.
基金supported by the Central government guides local funds for science and technology development (No. 2020L3023)the NSF of Fujian Province (No. 2018J01024), Youth Innovation Promotion Association, Chinese Academy of Sciences (CAS) (No. 2020310)+1 种基金the Fujian Institute of Research on the Structure of Matter and Institute of Urban Environment (FJIRSM&IUE) Joint Research Fund (No. RHZX-2019-001)the Science and Technology Planning Project of Xiamen City (No. 3502Z20191021)。
文摘The complete catalytic oxidation of formaldehyde (HCHO) to CO_(2)and H_(2)O at room temperature is a green route for indoor HCHO removal.Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area,intricate pores and high adsorption capacity.However,the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature.In this work,we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation.Activity tests illustrated that HCHO could be completely oxidized to CO_(2)and H_(2)O at a nearly 100%conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g·hr) at 25℃,when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L.The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction.The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene(DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.
基金supported by the National Natural Science Foun-dation of China(Nos.52073223,U1905215,52173065,22208332,22278324,and 52073034)the Project funded by China Post-doctoral Science Foundation(Nos.2021TQ0310,2022TQ0317,and 2022M712959)the Natural Science Foundation of Hubei Province of China(No.2022CFA001).
文摘The strong metal-support interaction(SMSI)plays a pivotal role in regulating electronic properties and activating surface oxygen species.In this work,we report light-irradiation-modulated SMSI for enhanced formaldehyde(HCHO)oxidation.Specifically,the SMSI between Pt nanoparticles(NPs)and Bi_(2)MoO_(6)cre-ated surface-active oxygen at Pt-Bi_(2)MoO_(6)interfaces to activate HCHO to dioxymethylene(DOM).Notably,light irradiation boosted the SMSI and catalytic activity.Moreover,photogenerated holes in Bi_(2)MoO 6 im-proved HCHO adsorption and activation,while photogenerated electrons migrated from Bi_(2)MoO_(6)to Pt NPs to promote O_(2)adsorption and activation,accelerating the oxidation of DOM to CO_(2)and H_(2)O.The light-modulated SMSI and the synergy between photocatalysis and thermocatalysis lead to enhanced cat-alytic oxidation activity,providing a practical strategy for indoor volatile organic compound(VOC)de-composition under ambient conditions.
基金This work was supported by the National Key R&D Program of China(2020YFA0710000)the National Natural Science Foundation of China(22122901,21902047)+1 种基金the Provincial Natural Science Foundation of Hunan(2020JJ5045,2021JJ20024,2021RC3054)the Shenzhen Science and Technology Program(JCYJ20210324140610028).
文摘Formate can be synthesized electrochemically by CO_(2) reduction reaction(CO_(2)RR)or formalde-hyde oxidation reaction(FOR).The CO_(2)RR approach suffers from kinetic-sluggish oxygen evolution reac-tion at the anode.To this end,an electrochemical sys-tem combining cathodic CO_(2)RR with anodic FOR was developed,which enables the formate electrosynthesis at ultra-low voltage.Cathodic CO_(2)RR employing the BiOCl electrode in H-cell exhibited formate Faradaic efficiency(FE)higher than 90% within a wide potential range from−0.48 to−1.32 V_(RHE).In flow cell,the current density of 100 mA cm^(−2) was achieved at−0.67 V_(RHE).The anodic FOR using the Cu_(2)O electrode displayed a low onset potential of−0.13 V_(RHE) and nearly 100%formate and H_(2) selectivity from 0.05 to 0.35 V_(RHE).The CO_(2)RR and FOR were constructed in a flow cell through membrane electrode assembly for the electrosynthesis of formate,where the CO_(2)RR//FOR delivered an enhanced current density of 100 mA cm^(−2) at 0.86 V.This work provides a promising pair-electrosynthesis of value-added chemicals with high FE and low energy consumption.
基金supported by the National Natural Science Foundation of China (21107124, 21337003)the Youth Innovation Promotion Association (2011037)Science Promotion Program of Research Center for Eco-Environmental Sciences, Chinese Academic Sciences (No. 121311RCEES-QN-20130046F)
文摘We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 nanosheets.The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet,including crystal steps and edges,thereby fixing the Au-TiO2 perimeter interface.Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 interface.The doped Au induced the formation of oxygen vacancies in the Au-TiO2 interface.Such vacancies are essential for generating active oxygen species（-＊O^-） on the TiO2 surface and Ti^3＋ ions in bulk TiO2.These ions can then form Ti^3＋-O^--Ti^4＋species,which are known to enhance the catalytic activity of formaldehyde（HCHO） oxidation.These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials.
基金supported by the Cultivating Project of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDPB1902)the Science and Technology Planning Project of Xiamen City(No.3502Z20191021)+1 种基金the Science and Technology Innovation“2025”major program in Ningbo(No.2022Z028)Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020310)。
文摘A series of α-MnO_(2) catalysts with various Mn valence states were treated by hydrogen reduction for different periods of time. Their catalytic capacity for formaldehyde(HCHO) oxidation was evaluated. The results indicated that hydrogen reduction dramatically improves the catalytic performance of α-MnO_(2) in HCHO oxidation. The α-MnO_(2) sample reduced by hydrogen for 2 h possessed superior activity and could completely oxidize 150 ppm HCHO to CO_(2) and H_(2)O at 70℃. Multiple characterization results illustrated that hydrogen reduction contributed to the production of more oxygen vacancies. The oxygen vacancies on the catalyst surface enhanced the adsorption, activation and mobility of O_(2) molecules, and thereby enhanced HCHO catalytic oxidation. This study provides novel insight into the design of outstanding MnO_x catalysts for HCHO oxidation at low temperature.
基金supported by the National Natural Science Foundation of China (51320105001, 51372190, 21573170, 51272199, 21433007)the National Basic Research Program of China (973 program, 2013CB632402)+2 种基金the Natural Science Foundation of Hubei Province (2015CFA001)the Fundamental Research Funds for the Central Universities (WUT: 2015-Ⅲ-034)Innovative Research Funds of SKLWUT (2015-ZD-1)~~
文摘Flower-like tin oxide-supported platinum（Pt/SnOx） with a hierarchical structure was synthesized by a hydrothermal method and characterized by XRD,SEM,TEM,high resolution TEM,XPS and nitrogen adsorption.The flower-like Pt/SnOx microspheres of 1 μm in diameter were composed of staggered petal-like nanosheets with a thickness of 20 nm.Pt nanoparticles（NPs） of 2-3 nm were well dispersed on the SnOx nanosheets.The catalyst was tested in the catalytic oxidation of gaseous formaldehyde（HCHO） at room temperature,and exhibited enhanced activity compared to Pt NPs supported on commercial SnO and ground SnOx.HCHO removal of 87%was achieved over the hierarchical Pt/SnOx after 1 h of reaction,which was 1.5 times that over the ground SnOx-supported Pt（Pt/g-SnOx）,and the high activity was maintained after six recycles,showing the high stability of this catalyst.HCHO decomposition kinetics was modeled as a second order reaction.The reaction rate constant for Pt/SnOx was 5.6 times higher than Pt/g-SnOx.The hierarchical pore structure was beneficial for the diffusion and adsorption of HCHO molecules,and the highly dispersed Pt NPs on the SnOx nanosheets were the active sites for the oxidative decomposition of HCHO into CO2 and H2O.This study provided a promising approach for designing efficient catalysts for indoor HCHO removal at ambient temperature.
文摘Through the impregnation method, Ag catalysts with different support (such as TiO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub>) were prepared and then tested for catalytic oxidation of formaldehyde (HCHO) at low temperatures. The Ag/TiO<sub>2</sub> catalyst exhibited strong catalytic performance, converting HCHO to CO<sub>2</sub> and H<sub>2</sub>O at around 95°C. However, the Ag/Al<sub>2</sub>O<sub>3</sub> catalysts showed much lower activity and reached 100% conversion at 125°C. The Ag-based catalysts were next characterized by several methods (XRD, TEM, FT-R, BET and H<sub>2</sub>-TPR). Results of characterization revealed that support dramatically impacts the size and dispersion of Ag particles. The XRD analysis showed the existence of different peaks of the silver on the surface of Al<sub>2</sub>O<sub>3</sub> in the contrast with TiO<sub>2</sub> no specific peaks exist. Therefore, the size of the Ag particles and their dispersion are the most important factors that affect their catalytic performance for formaldehyde oxidation. In terms of catalytic performance for HCHO oxidation, the Ag/TiO<sub>2 </sub>catalyst possesses the best Ag dispersion, as well as the smallest Ag particle size.
基金the National Natural Science Foundation of China(No.22372104)the Shenzhen Science and Technology Program(Nos.ZDSYS20220527171401003 and KQTD20190929173914967)+1 种基金Guangdong College Students Science and Technology Innovation Cultivation Special Fund Project(No.pdjh2024a315)The authors also acknowledge the Instrumental Analysis Center of Shenzhen University(Xili Campus)for their assistance on TEM observation.
文摘The formaldehyde oxidation reaction(FOR)on a Cu-based electrocatalyst enables hydrogen(H_(2))at the anode in OH−solution,facilitating a bipolar H_(2) production system at ultra-low electrolysis voltage.However,the specific impact of*OH adsorption on the Cu surface regarding the FOR has been rarely investigated.Herein,the strong*OH adsorption Cu(S-OH Cu)electrode,which exhibits high activity and excellent stability of FOR,is developed to investigate the specific impact of*OH adsorption on the Cu surface during the FOR process.Impressively,the increased*OH adsorption on the Cu electrode,typically regarded as a poisoning effect that diminishes inherent FOR activity by reducing the adsorption of intermediate reactants,is firstly revealed as an OH-induced favorable reconstruction effect that significantly improves FOR stability.Specifically,the dual functions of OH-induced favoring reconstruction include accelerating the phase transition of the Cu(0)/Cu(I)redox cycle to refresh the active site and optimizing surface reconstruction to preferentially generate Cu(220)with stronger adsorption energy for H_(2)C(OH)O*and lower C−H barrier energy during FOR.This work provides a promising strategy for designing stable Cu electrocatalysts for FOR to produce hydrogen with extremely low energy input.
基金supported by the National Natural Science Foundation of China(21577088)~~
文摘Co3O4 catalysts prepared with different precipitants（NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3）were investigated for the oxidation of formaldehyde（HCHO）.Among these,KHCO3-precipitated Co3O4（KHCO3-Co） was the most active low-temperature catalyst,and was able to completely oxidize HCHO at the 100-ppm level to CO2 at 90℃.In situ diffuse reflectance infrared spectroscopy demonstrated that hydroxyl groups on the catalyst surface were regenerated by K~＋ and CO3^（2-）,thus promoting the oxidation of HCHO.Moreover,H2-temperature programmed reduction and X-ray photoelectron spectroscopy showed that employing KHCO3 as the precipitant increased the Co^3＋/Co^2＋molar ratio on the surface of the Co3O4 catalyst,thus further promoting oxidation.Structural characterization revealed that catalysts precipitated with carbonate or bicarbonate reagents exhibited greater specific surface areas and pore volumes.Overall,these data suggest that the high activity observed during the Co3O4 catalyzed oxidation of HCHO can be primarily attributed to the presence of K~＋ and CO3^（2-） on the Co3O4 surface and the favorable Co^3＋/Co^2＋ ratio.
基金supported by the Sanming University(No.23YG05)the Science Foundation of Fujian Province(No.2023J011027).
文摘Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO oxidation,yet suffer from low metal utilization.Efforts focus on designing catalysts with enhanced intrinsic activity and reduced noble metal loading.In this study,we developed a simple pretreatment method using ammonia solution on SiO_(2)carrier to enhance the activity of the Pd/SiO_(2)catalyst for HCHO oxidation.After the carrier was pretreated with an ammonia solution,a significant promoting effect was observed on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst.It achieved almost complete oxidation of 150 ppmV of HCHO at 25℃,much better than the Pd/SiO_(2)-R(5%HCHO conversion rate).Multiple characterization results indicated that the ammonia solution pretreatment of the SiO_(2)carrier increased the surface defects,facilitating the anchoring of Pd nanoparticles and increasing their dispersion.The increase dispersion of Pd resulted in the generation of additional oxygen vacancies on the catalyst surfaces.The increased in oxygen vacancies on the catalyst was beneficial for enhancing the catalyst's ability to activate H_(2)O to form surface hydroxyl groups,thereby accelerating the catalytic oxidation process of HCHO.The reaction mechanism of HCHO on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst mainly follows an efficient pathway:firstly,the HCHO being oxidized by surface active hydroxyl groups to formate;subsequently,the formate being oxidized by hydroxyl groups to H_(2)O and CO_(2).This study provides a promising strategy for designing high-performance noble metal catalysts for HCHO catalytic oxidation.
基金supported by the National Natural Science Foundation of China (No. 20871118,21007076)the Knowledge Innovation Program of the Chinese Academy of Sciences (CAS) (No. KSCX2-YW-G-059)+1 种基金the National Basic Research Program (973) of China (No.2010CB934103)the "Hundred Talents Program" of CAS
文摘Flaky and nanospherical birnessite and birnessite-supported Pt catalysts were successfully prepared and characterized by means of Xray diffraction （XRD）,transmission electron microscopy （TEM）,energy dispersive spectroscopy （EDS） and N2 adsorption-desorption.Effects of the birnessite morphology and Pt reduction method on the catalytic activity for the complete oxidation of formaldehyde （HCHO） were investigated.It was found that flaky birnessite exhibited higher catalytic activity than nanospherical birnessite.The promoting effect of Pt on the birnessite catalyst indicated that the reduction method of the Pt precursor greatly influenced the catalytic performance.Flaky birnessite-supported Pt nanoparticles reduced by KBH 4 showed the highest catalytic activity and could completely oxidize HCHO into CO2 and H2O at 50℃,whereas the sample reduced using H2-plasma showed lower activity for HCHO oxidation.The differences in catalytic activity of these materials were jointly attributed to the effects of pore structure,surface active sites exposed to HCHO and the dispersion of Pt nanoparticles.
基金This work is financially supported by the National Natural Science Foundation of China （Grant Nos. 21107124 and 21337003）, Dean＇s Award Startup Funds of the Chinese Academy of Sciences, the National High Technology Research and Development Program of China （No. 2012AA063101）, and Science Promotion Program of Research Center for Eco-Environmcntal Sciences, CAS （YSW2013B05）.
文摘MnO2 microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO2 catalysts were synthesized using the sol-gel method. We obtained three MnO2 microspheres and Au/MnO2 samples： coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO2 are the main factor affecting the catalytic activities of these samples, and γ- MnO2 shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO2. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO2. We also studied intermediate species. The dioxymethylene （DOM） and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO2. A proposed mechanism of formaldehyde oxidation over Au/MnO2 catalysts was also obtained.
基金supported by the Doctoral Program of Xi'an Shiyou University(134010155)Shaanxi Provincial College Students'Inno vative Entrepreneurial Training Program(No.2016107051360 and 201610705046)
文摘A series of CeO2-Co3O4 mixed oxide catalysts with different Co/（Co＋Ce） atomic ratios were synthesized by citric acid sol-gel method and used for catalytic oxidation of formaldehyde（HCHO）. Many techniques such as Brumauer-Emmett-Teller（BET）, X-ray diffraction（XRD）, scanning electron microscopy（FE-SEM）, temperature programmed reduction（H_2-TPR）, temperature-programmed desorption（O_2-TPD） and X-ray photoelectron spectroscopy（XPS） were used to characterize catalysts. The results of catalytic performance tests showed that the catalyst CeO_2-Co_3O_4 with Co/（Co＋Ce） ratio of 0.95 exhibited the best performance, and the temperature of complete oxidation of HCHO was 80 oC. The analytical results indicated that the addition of CeO_2 enhanced the specific surface area of Co_3O_4 and the fine dispersion of both of them. Moreover, the strong interaction between CeO_2 and Co_3O_4 resulted in the unique redox properties, which enhanced the available surface active oxygen and led to high valence state of cobalt oxide species. All those effects played crucial roles in the excellent performance of CeO_2-Co_3O_4 for the HCHO oxidation.
基金The work was supported by the National Natural Science Foundation of China(Nos.22176166 and 22179034)the Natural Science Foundation of Heilongjiang Province(No.ZD2023B002).
文摘Formaldehyde oxidation reaction(FOR)is a promising reaction alternative to the anodic oxygen evolution reaction(OER)owing to its ultra-low electrolysis potential and ability to produce formate and hydrogen gas.In this work,the electrode for FOR is prepared using Ag/Ag_(2)O nanoparticles(Ag/Ag_(2)O NPs)covered with Nafion membrane as the catalysts modified onto nickel foam(NF).Ag/Ag_(2)O NPs@NF exhibits significantly higher FOR activity than Ag NPs@NF and Ag_(2)O NPs@NF.At 100 mA·cm^(-2),the FOR potential on the Ag/Ag_(2)O NPs@NF electrode is only 0.16 V(vs.RHE).Meanwhile,the Faradaic efficiencies can reach up to 100% for both formate and H_(2) produced by FOR.Density functional theory(DFT)calculations indicate that the Ag/Ag_(2)O heterostructure exhibits lower reaction energy barriers for generating formate and H2 than pure Ag and Ag_(2)O.This work introduces a new synthetic approach for developing novel FOR catalysts and offers insights into the potential application prospects of FOR.
基金supported by the State Key Laboratory of Materials Low-Carbon Recycling,Beijing University of Technologysponsored by the Beijing Nova Program(20240484638),China。
文摘Replacing the oxygen evolution reaction(OER)with the anodic formaldehyde oxidation reaction(FOR)is crucial for achieving low-voltage dual-electrode hydrogen evolution.However,existing FOR catalysts face challenges such as low activity,high transition state barriers,and unclear reaction mechanisms.In this study,a three-dimensional nano-composite Cu_(2)O/Cu/Mn_(2)O_(3)heterogeneous catalyst with enhanced hydrogen spillover effect was synthesized through hydrothermal and photosensitive oxidation treatment techniques.The catalyst consists of~20 nm Cu_(2)O/Cu and 30-70 nm Mn_(2)O_(3)nanoparticles.The hydrogen spillover effect enhanced Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst demonstrated outstanding FOR performance,with an anode potential of only 0.128 V at a current density of 100 mA cm^(-2),significantly lower than that of the Cu_(2)O/Cu-CC catalyst(0.25 V)and the OER potential(1.726 V).Moreover,the Faraday efficiency of the Cu_(2)O/Cu/Mn_(2)O_(3)(1:1)electrocatalyst reached~100%.The electrocatalyst’s FOR performance remains stable over 50 h without decay,and its hydrogen evolution reaction(HER)performance surpasses that of Cu and MnOxelectrocatalysts.Density functional theory(DFT)calculations suggested that the Cu_(2)O/Cu/Mn_(2)O_(3)catalyst significantly lowers the energy barriers for C-H bond breaking(0.48 eV)and H-H bond formation(-0.99 eV)by promoting the hydrogen spillover effect.This study provides theoretical support for designing efficient and stable low-energy dual-electrode hydrogen evolution catalysts and validates their potential through experiments.
文摘Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.
文摘Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.
基金supported by the National Natural Science Foundation of China(21477023)the Science and Technology Commission of Shanghai Municipality(14JC1400400)~~
文摘Top‐down synthesis has been used to prepare catalytic materials with nanometer sizes,but fabricating atomically dispersed metal catalysts remains a challenge because surface single metal atoms are prone to aggregation or coalescence.A top‐down strategy is used to synthesize atomically dispersed metal catalysts,based on supported Ag nanoparticles.The changes of the geometric and electronic structures of the Ag atoms during the top‐down process are studied using the in situ synchrotron X‐ray diffraction technique,ex situ X‐ray absorption spectroscopy,and transmission electron microscopy.The experimental results,coupled with the density functional theory calculations,demonstrate that the electronic perturbation of the Ag frontier orbitals,induced by the Ag‐O interactions at the perimeter of the metal‐support interface,is the driving force of the top‐down process.The top‐down synthesis has two important functions:to increase the number of catalytic active sites and to facilitate the study of complex reaction mechanisms(e.g.,formaldehyde oxidation)by developing single‐site model catalysts.
