摘要
Developing efficient photocatalysts for CO_(2)conversion under full-spectrum irradiation remains a key challenge for solar-to-chemical energy conversion.In this study,a novel S-scheme heterojunction composed of reduction Cs_(0.32)WO_(3)(CWO)nanosheets with hexagonal structure and oxidation WO_(3)·2H_(2)O(WO)nanorods with monoclinic structure photocatalyst was successfully constructed via an ultrasound strategy.Under full-spectrum irradiation for 4 h,the optimized 2D/1D of heterostructure CWO/WO-0.8 exhibited superior photocatalytic performance,achieving CO and CH_(3)OH yields of 29.74 and 63.71μmol·g^(-1),respectively.The enhanced activity is primarily ascribed to the formation of an S-scheme charge transfer pathway,which facilitates efficient separation and directional migration of photogenerated charge carriers through the internal electric field at the CWO/WO interface.This process facilitates the electron enrichment on the CWO surface and significantly enhances its CO_(2)reduction ability.Besides,the results of various characterizations show that CWO/WO-0.8 possesses enhanced optical response capability.The results of density functional theory calculations and CO_(2)-temperature programmed desorption analysis confirmed that the CWO/WO heterojunction exhibits stronger CO_(2)adsorption and activation abilities compared to the pristine CWO and WO.The reaction pathway for CH_(3)OH production was elucidated by in-situ diffused reflectance Fourier transformed infrared tests.This work provides new insights into the rational design of S-scheme photocatalysts for efficient and selective CO_(2)conversion.
摘要:近年来,碳资源高值化利用与太阳能转化技术的深度融合为绿色能源体系的构建提供了全新发展路径.特别是以太阳能驱动的CO_(2)还原反应,因其可实现温室条件下的气体资源化利用与清洁燃料协同生成,成为应对能源危机与环境问题的潜在解决方案.然而,CO_(2)分子热力学稳定性高、动力学活化难度大,且其还原过程涉及多电子和多质子协同转移,导致在温和条件下实现高效且高选择性的转化仍面临巨大挑战.目前多数光催化体系存在光生载流子易复合、界面协同效应弱、CO_(2)吸附活化能力差等问题,严重制约了其催化效率和产物选择性.因此,构建具有合理能带匹配关系、显著界面耦合效应和优异电荷分离能力的新型异质结光催化剂,成为提升CO_(2)光还原性能、推动该领域突破的重要研究方向.本文采用超声辅助策略,构建了一种新型S型异质结光催化剂,由具备六方结构的还原型Cs_(0.33)WO_(3)(CWO)纳米片与单斜结构的氧化型WO_(3)·2H_(2)O(WO)纳米棒复合形成.通过调控复合比例,获得了最优催化剂CWO/WO-0.8(CWO与WO的质量比为80%),其在全光谱照射条件下表现出优异的CO_(2)光还原性能,在反应4 h后,CH_(3)OH与CO的生成量分别达到63.71和29.74μmol·g^(-1),远优于纯CWO或WO组分.光催化性能的显著提升归因于两组分间形成的S型电荷转移路径,该路径在界面处引发内建电场,有效抑制了光生电子与空穴的复合,促进载流子的高效分离与定向迁移,使得电子在CWO表面富集,从而增强了CO_(2)分子的吸附与还原活性.通过紫外-可见漫反射光谱和瞬态光电流等光物理测试手段发现,该异质结体系在可见光及近红外区域具有更强的光吸收能力与更优的光生电子利用率;开尔文探针力显微镜与飞秒瞬态吸收光谱测试分析进一步验证了界面处的内建电场增强了电子传输能力.密度泛函理论计算与CO_(2)程序升温脱附分析表明,CWO/WO异质结比各单一组分更易与CO_(2)发生物理和化学吸附,具备更强的CO_(2)活化能力.进一步通过原位漫反射红外光谱追踪反应过程,成功监测到CO_(2)还原中间体,并揭示了CH_(3)OH生成过程中的可能路径.研究还表明,反应中S型电子传输行为在促进逐步电子转移过程中起到关键作用,进而有效提升了反应的选择性与产率.综上,本研究通过构建具有内建电场的S型异质结CWO/WO,实现了CO_(2)在全光谱照射条件下的高效还原转化,成功合成了以CH_(3)OH为主的高附加值产物,拓展了光驱动CO_(2)转化的新策略,并为后续高效异质结光催化剂的构筑及机理研究提供了理论依据与实验参考.
基金
国家自然科学基金(22361132537,92163125)
湖北省科技创新人才计划(2023DJC35).
