物理化学学报2023，Vol.39Issue(6)：135-144,10.DOI:10.3866/PKU.WHXB202212026
Pt-C3N4/BiOCI S型异质结应用于光催化CO2还原的理论计算研究
A DFT Study on S-Scheme Heterojunction Consisting of Pt Single Atom Loaded G-C3N4 and BiOCI for Photocatalytic CO2 Reduction
摘要
Abstract
Photocatalytic CO2 reduction to renewable hydrocarbon fuels provides a feasible protocol for alleviating the greenhouse effect and addressing energy shortage.However,the CO2 reduction activity of a single-component photocatalyst is very low because of two problems.One is the fast recombination of photogenerated charge carriers,which leads to low photon efficiency,while the other is the large energy barrier to CO2 activation.There have been considerable research efforts to develop photocatalysts with improved CO2 reduction performance.For example,step-scheme(S-scheme)heterojunctions have been developed to improve charge carrier separation and enhance the redox abilities of photocatalysts.Single-atom metals have also been applied cocatalysts to optimize the reaction thermodynamics.Thus,the synergy between S-scheme heterojunctions and single-atom metal cocatalysts is anticipated to promote both charge carrier transfer and CO2 reduction reaction processes.In this study,a Pt-C3N4/BiOCI heterojunction photocatalyst is modeled,composed of single-atom Pt-loaded g-C3N4 and BiOCI,and its photocatalytic properties are studied using density functional theory calculations.Its structure and electronic property are explored,and the process of CO2 conversion is also simulated.The charge density difference results show that electrons in g-C3N4 are transferred to BiOCI owing to the higher Fermi level of g-C3N4 than that of BiOCI.Therefore,an interfacial electric field from g-C3N4 to BiOCI is established at the g-C3N4/BiOCI interface.Under light irradiation,charge carrier transfer in the g-C3N4/BiOCI composite is consistent with the S-scheme mechanism.Specifically,the photogenerated electrons in the CB of BiOCI recombine with the photogenerated holes in the VB of g-C3N4,while the photogenerated electrons in the CB of g-C3N4 and the photogenerated holes in the VB of BiOCI are retained.After the loading of Pt atom at each sixfold cavity of g-C3N4,the work function of g-C3N4 decreases,thereby enlarging the difference between the Fermi levels of the two semiconductors.Consequently,more electrons are transferred from Pt-C3N4 to BiOCI,and the strength of the interfacial electric field is increased.This enhanced electric field is beneficial to the S-scheme charge transfer in Pt-C3N4/BiOCI heterojunctions.Besides,based on the calculated variation in reaction energy,the rate-limiting step involved in CO2 reduction on g-C3N4/BiOCI heterojunction is the hydrogenation of CO2 to COOH,which has an energy barrier of 1.13 eV.After Pt loading,the hydrogenation of CO to HCO is the rate-limiting step and the corresponding energy increase is 0.71 eV.These results manifest that the introduction of Pt single-atom cocatalysts improves the CO2 reduction performance of g-C3N4/BiOCI S-scheme photocatalysts by strengthening the interfacial electric field and reducing the energy barrier.This study provides guidance for constructing metal-atom-incorporated S-scheme heterojunction photocatalysts to realize efficient CO2 reduction.关键词
S型异质结/密度泛函理论/光催化CO2还原/单原子Pt/氮化碳/BiOCI/内建电场Key words
Step-scheme heterojunction/Density functional theory/Photocatalytic CO2 reduction/Single-atom Pt/Carbon nitride/Bismuth oxychloride/Internal electric field分类
化学化工引用本文复制引用
罗铖,龙庆,程蓓,朱必成,王临曦..Pt-C3N4/BiOCI S型异质结应用于光催化CO2还原的理论计算研究[J].物理化学学报,2023,39(6):135-144,10.基金项目
This work was supported by the National Key Research and Development Program of China(2022YFB3803600,2022YFE0115900),National Natural Science Foundation of China(22238009,51932007,52173065,21905219,22208332,22278324),Natural Science Foundation of Hubei Province of China(2022CFA001),China Postdoctoral Science Foundation(2022M710137),and Innovative Research Funds of SKLWUT,China(2022-CL-A1-01).国家重点研发计划(2022YFB3803600,2022YFE0115900),国家自然科学基金(22238009,51932007,52173065,21905219,22208332,22278324),湖北省自然科学基金(2022CFA001),中国博士后科学基金(2022M710137)和武汉理工大学自主创新研究基金(2022-CL-A1-01)资助 （2022YFB3803600,2022YFE0115900）
