物理化学学报2021，Vol.37Issue(6)：148-156,9.DOI:10.3866/PKU.WHXB202010027
理论计算研究二维/二维BP/g-C3N4异质结的光催化CO2还原性能
2D/2D Black Phosphorus/g-C3N4 S-Scheme Heterojunction Photocatalysts for CO2 Reduction Investigated using DFT Calculations
摘要
Abstract
Photocatalytic reduction of CO2 to hydrocarbon compounds is a promising method for addressing energy shortages and environmental pollution.Considerable efforts have been devoted to exploring valid strategies to enhance photocatalytic efficiency.Among various modification methods,the hybridization of different photocatalysts is effective for addressing the shortcomings of a single photocatalyst and enhancing its CO2 reduction performance.In addition,metal-free materials such as g-C3N4 and black phosphorus (BP) are attractive because of their unique structures and electronic properties.Many experimental results have verified the superior photocatalytic activity of a BP/g-C3N4 composite.However,theoretical understanding of the intrinsic mechanism of the activity enhancement is still lacking.Herein,the geometric structures,optical absorption,electronic properties,and CO2 reduction reaction processes of 2D/2D BP/g-C3N4 composite models are investigated using density functional theory calculations.The composite model consists of a monolayer of BP and a tri-s-triazine-based monolayer of g-C3N4.Based on the calculated work function,it is inferred that electrons transfer from g-C3N4 to BP owing to the higher Fermi level of g-C3N4 compared with that of BP.Furthermore,the charge density difference suggests the formation of a built-in electric field at the interface,which is conducive to the separation of photogenerated electron-hole pairs.The optical absorption coefficient demonstrates that the light absorption of the composite is significantly higher than that of its single-component counterpart.Integrated analysis of the band edge potential and interfacial electronic interaction indicates that the migration of photogenerated charge carriers in the BP/g-C3N4 hybrid follows the S-scheme photocatalytic mechanism.Under visible-light irradiation,the photogenerated electrons on BP recombine with the photogenerated holes on g-C3N4,leaving photogenerated electrons and holes in the conduction band of g-C3N4 and the valence band of BP,respectively.Compared with pristine g-C3N4,this S-scheme heterojunction allows efficient separation of photogenerated charge carriers while effectively preserving strong redox abilities.Additionally,the possible reaction path for CO2 reduction on g-C3N4 and BP/g-C3N4 is discussed by computing the free energy of each step.It was found that CO2 reduction on the composite occurs most readily on the g-C3N4 side.The reaction path on the composite is different from that on g-C3N4.The heterojunction reduces the maximum energy barrier for CO2 reduction from 1.48 to 1.22 eV,following the optimal reaction path.Consequently,the BP/g-C3N4 heterojunction is theoretically proven to be an excellent CO2 reduction photocatalyst.This work is helpful for understanding the effect of BP modification on the photocatalytic activity of g-C3N4.It also provides a theoretical basis for the design of other high-performance CO2 reduction photocatalysts.关键词
光催化/CO2还原/S型异质结/g-C3N4/理论计算Key words
Photocatalysis/CO2 reduction/Step-scheme heterojunction/Graphitic carbon nitride/Density functional theory分类
化学化工引用本文复制引用
费新刚,谭海燕,程蓓,朱必成,张留洋..理论计算研究二维/二维BP/g-C3N4异质结的光催化CO2还原性能[J].物理化学学报,2021,37(6):148-156,9.基金项目
This work was supported by the National Key Research and Development Program of China (2018YFB1502001),the National Natural Science Foundation of China (51872220,21905219,51932007,U1905215,21871217,U1705251),National Postdoctoral Program for Innovative Talents (BX20180231),China Postdoctoral Science Foundation (2020M672432),Hubei Postdoctoral Program for Innovative Research Post.国家重点研发计划(2018YFB 1502001),国家自然科学基金(51872220,21905219,51932007,U1905215,21871217,U1705251),博士后创新人才支持计划(BX20180231),中国博士后科学基金(2020M672432)和湖北省博士后创新研究岗位项目资助 （2018YFB1502001）
