Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
J Chem Phys. 2019 Nov 14;151(18):180901. doi: 10.1063/1.5124710.
Semiconductor photoelectrochemistry is a fascinating field that deals with the chemistry and physics of photodriven reactions at solid/liquid interfaces. The interdisciplinary field attracts (electro)chemists, materials scientists, spectroscopists, and theorists to study fundamental and applied problems such as carrier dynamics at illuminated electrode/electrolyte interfaces and solar energy conversion to electricity or chemical fuels. In the pursuit of practical photoelectrochemical energy conversion systems, researchers are exploring inexpensive, solution-processed semiconductor nanomaterials as light absorbers. Harnessing the enormous potential of nanomaterials for energy conversion applications requires a fundamental understanding of charge carrier generation, separation, transport, and interfacial charge transfer at heterogeneous nanoscale interfaces. Our current understanding of these processes is derived mainly from ensemble-average measurements of nanoparticle electrodes that report on the average behavior of trillions of nanoparticles. Ensemble-average measurements conceal how nanoparticle heterogeneity (e.g., differences in particle size, shape, and surface structure) contributes to the overall photoelectrochemical response. This perspective article focuses on the emerging area of single particle photoelectrochemistry, which has opened up an exciting new frontier: direct investigations of photodriven reactions on individual nanomaterials, with the ability to elucidate the role of particle-dependent properties on the photoelectrochemical behavior. Here, we (1) review the basic principles of photoelectrochemical cells, (2) point out the potential advantages and differences between bulk and nanoelectrodes, (3) introduce approaches to single nanoparticle photoelectrochemistry and highlight key findings, and (4) provide our perspective on future research directions.
半导体光电化学是一个迷人的领域，涉及固/液界面光驱动反应的化学和物理。这个跨学科领域吸引了（电化学）、材料科学家、光谱学家和理论学家来研究基本和应用问题，如光照电极/电解质界面的载流子动力学和太阳能转化为电能或化学燃料。在探索实用的光电化学能量转换系统的过程中，研究人员正在探索廉价的、溶液处理的半导体纳米材料作为光吸收剂。要利用纳米材料在能量转换应用中的巨大潜力，需要对异质纳米尺度界面上的载流子产生、分离、传输和界面电荷转移有基本的了解。我们目前对这些过程的理解主要来自于对纳米颗粒电极的整体平均测量，这些测量报告了万亿个纳米颗粒的平均行为。整体平均测量掩盖了纳米颗粒的异质性（例如，颗粒大小、形状和表面结构的差异）如何影响整体光电化学响应。本文聚焦于单颗粒光电化学这一新兴领域，它开辟了一个令人兴奋的新前沿：可以直接研究单个纳米材料的光驱动反应，从而阐明颗粒依赖性性质对光电化学行为的作用。在这里，我们（1）回顾光电化学电池的基本原理，（2）指出体相和纳米电极的潜在优势和区别，（3）介绍单纳米颗粒光电化学的方法并强调关键发现，以及（4）提供对未来研究方向的看法。
