构建双通道路径增强iCOF/Bi_(2)O_(3)S型异质结在纯水体系中光催化合成H_(2)O_(2)性能

Improving Photocatalytic H_(2)O_(2) Production over iCOF/Bi_(2)O_(3) S-Scheme Heterojunction in Pure Water via Dual Channel Pathways

太阳能光催化技术是一种绿色、经济、可持续的制备H_(2)O_(2)方法,被认为是取代传统蒽醌法最有前景的策略。然而,由于有限的光捕获能力、快速的光生载流子复合以及氧化还原能力不足等问题,单一组分光催化剂表现出温和的光催化活性。并且,在光催化合成H_(2)O_(2)反应系统中需要额外添加牺牲剂。在这项研究中,我们通过光沉积法将Bi_(2)O_(3)(BO)纳米颗粒负载于离子型有机共价框架材料(iCOF)纳米纤维上,构建一种S型异质结用于双通道路径光催化合成H_(2)O_(2)。在纯水体系中,在iCOF表面负载10 wt%BO时,复合催化剂iCOF/BO10表现出最高的H_(2)O_(2)产率,达到了9.76 mmol·g^(-1)·h^(-1)(在420 nm处的量子效率为5.5%)。这一性能分别是纯iCOF的2.2倍,纯BO的5.6倍。原位表征技术(包括原位X射线光电子能谱、DFT理论计算、活性物种捕获实验以及原位漫反射红外傅里叶变换光谱)揭示该S型异质结不仅能促进光生载流子的分离和增强光吸收能力,而且能实现氧化还原能力最大化,使得反应体系同时通过间接2e^(-)氧气还原反应和4e^(-)水氧化反应双通道路径产生H_(2)O_(2)。此外,4e^(-)水氧化反应生成的O_(2)能够通过间接2e^(-)氧气还原反应加快H_(2)O_(2)生成的反应动力学,实现光催化H_(2)O_(2)的全合成。该项工作为开发新颖催化剂实现高效光催化合成H2O_(2)提供了独特的见解。

Solar photocatalysis is a green,economical,and sustainable method for H_(2)O_(2) synthesis,which has been regarded as the most promising alternative to the traditional anthraquinone oxidation method.However,single-component photocatalyst exhibits moderate activity owing to the limited light-harvesting range,fast charge recombination and inadequate redox capacity.Moreover,the addition of sacrificial agents is required in the reaction system.Herein,we present the development of an S-scheme heterojunction,achieved through photodepositing Bi_(2)O_(3) nanoparticles(BO)on ionic covalent organic framework nanofiber(iCOF).The optimized photocatalyst iCOF/BO10 shows the highest H_(2)O_(2) production performance in pure water,achieving an H_(2)O_(2) yield of 9.76 mmol·g^(-1)·h^(-1) with an apparent quantum yield(AQY)of 5.5% at 420 nm.This photocatalytic performance is approximately 2.2 and 5.6 times as high as that of pristine iCOF and BO,respectively.In-depth characterizations including in situ irradiated XPS,DFT-calculations,active species trapping experiments and in situ DRIFTS,reveal that the obtained sample not only facilitates charge carrier separation and enhances light absorption capability,but also maximizes the redox ability to concurrently achieve indirect 2e^(-)ORR and 4e^(-)WOR for H_(2)O_(2) production.Additionally,the generated O_(2) from the 4e^(-)WOR is capable of accelerating the reaction kinetics for H_(2)O_(2) formation via the indirect 2e^(-)ORR pathway,enabling overall photocatalytic H_(2)O_(2) synthesis.This work provides a new insight into creating innovative catalysts for achieving highefficiency photosynthesis of H_(2)O_(2).