压电极化增强光催化能源转化的研究进展

Advances in Piezoelectric Polarization Enhanced Photocatalytic Energy Conversion

半导体光催化技术是缓解能源过度消耗和修复生态环境破坏的有效途径。然而,强大的库仑引力导致光生载流子迅速复合,降低了太阳能转化效率。压电光催化通过耦合压电效应和半导体光激发特性实现了电荷载流子动力学的有效调控。机械应力诱导的压电极化电场促进了载流子在体相和表面的分离,有效调节了界面的电荷迁移行为,提高了光催化反应活性。本文主要介绍压电极化促进光催化活性的机制,基于压电光催化的反应过程重点总结了增强催化活性的有效策略,包括形貌调控、极化调控、异质结构建和表面工程,并聚焦能源应用展示了压电光催化的最新进展。最后,对压电光催化的未来发展和挑战进行了分析和展望。

Semiconductor-based photocatalysis is an efficient technology that reduces energy consumption and environmental pollution;however,it is impeded by Coulombic attraction-induced charge recombination,which reduces solar conversion efficiency.The internal electric field induced by heterointerface engineering,defect engineering,heteroatom doping,ferroelectric polarization,and polar surface terminations intervening in the uniform charge distribution can drive the directional migration of photogenerated electrons and holes,suppressing the charge recombination and back-reaction of intermediate species.However,the built-in electric field is static and easily shielded by internal active carriers and externally charged ions,which is detrimental to successive charge separation.Moreover,the internal electric field that relies solely on the structural design of the catalyst often requires complex preparation processes and is disqualified from simple and efficient solar energy conversion.By coupling the piezoelectric effect with the photoexcitation feature in piezo-photocatalysis,charge carrier dynamics can be persistently modulated.The noncentrosymmetric structures of piezoelectrics result in the deviation of positive and negative charge centers with the exerted external stress,generating nonzero dipole moments and polarization charges on the opposite terminals of the crystal.On the one hand,the polarized bound charges and initiated piezoelectric polarization field by mechanical stress promote the separation and transfer of photoinduced charges in both the bulk and on the surface of the catalyst,facilitating more active carriers to participate in the surface reaction.On the other hand,the accumulation of piezoelectric polarization charges on the surface contributes to the upward or downward bending of the band,which can flexibly manipulate the charge transfer behavior at the heterojunction interface,further steering the spatial distribution of electrons and holes.In addition,band tilting induced by piezoelectric polarization can also modulate the energy band structure of the catalyst to match the redox potential of the target reaction,breaking the intrinsic thermodynamic restriction.Hence,the coupling of solar and mechanical energy significantly improves the efficiency of catalytic energy conversion.As a complex reaction process of piezo-photocatalysis,diverse enhancement strategies have been implemented;however,there are few systematic and pertinent overviews for high-performance piezo-photocatalyst design.This study introduces the mechanism of piezoelectric polarization-enhanced photocatalysis and summarizes the catalytic enhancement strategy based on the piezo-photocatalysis reaction process,including morphology and polarization regulation,heterostructure construction,and surface engineering.Meanwhile,recent advances in piezo-photocatalysis for energy applications have been reviewed.Finally,the problems and challenges associated with the development of piezo-photocatalysis are analyzed and discussed.