Key Lab of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China.
Nanoscale. 2019 Oct 25;11(41):18968-18994. doi: 10.1039/c9nr03474a.
Hydrogen production from photoelectrochemical (PEC) water splitting using semiconductor photocatalysts has attracted great attention to realize clean and renewable energy from solar energy. The visible light response of WO3 with a long hole diffusion length (∼150 nm) and good electron mobility (∼12 cm2 V-1 s-1) makes it suitable as the photoanode. However, WO3 suffers from issues including rapid recombination of photoexcited electron-hole pairs, photo-corrosion during the photocatalytic process due to the formation of peroxo-species, sluggish kinetics of photogenerated holes, and slow charge transfer at the semiconductor/electrolyte interface. This work highlights the approaches to overcome these drawbacks of WO3 photoanodes, including: (i) the manipulation of nanostructured WO3 photoanodes to decrease the nanoparticle size to promote hole migration to the WO3/electrolyte interface which benefits the charge separation; (ii) doping or introducing oxygen vacancies to improve electrical conductivity; exposing high energy crystal surfaces to promote the consumption of photogenerated holes on the high-active crystal face, thereby suppressing the recombination of photogenerated electrons and holes; (iii) decorating with co-catalysts to reduce the overpotential which inhibits the formation of peroxo-species; (iv) other methods such as coupling with narrow band semiconductors to accelerate the charge separation and controlling the crystal phase via annealing to reduce defects. These approaches are reviewed with detailed examples.
利用半导体光催化剂进行光电化学（PEC）水分解制氢，引起了人们极大的关注，以实现从太阳能中获取清洁和可再生能源。WO3 具有长空穴扩散长度（∼150nm）和良好的电子迁移率（∼12cm2V-1s-1），可见光响应，使其适合用作光阳极。然而，WO3 存在一些问题，包括光生电子-空穴对的快速复合、光催化过程中由于过氧物种的形成而导致的光腐蚀、光生空穴的动力学缓慢以及半导体/电解质界面处的电荷转移缓慢。这项工作强调了克服 WO3 光阳极这些缺点的方法，包括：（i）操纵纳米结构 WO3 光阳极，减小纳米颗粒尺寸，促进空穴向 WO3/电解质界面迁移，有利于电荷分离；（ii）掺杂或引入氧空位以提高电导率；暴露高能晶面，促进高活性晶面上光生空穴的消耗，从而抑制光生电子和空穴的复合；（iii）用共催化剂修饰，降低抑制过氧物种形成的过电位；（iv）通过耦合窄带半导体、退火控制晶相等其他方法来加速电荷分离并减少缺陷。通过详细的例子对这些方法进行了综述。
