Jun Sang Eon, Hong Seung-Pyo, Choi Seokhoon, Kim Changyeon, Ji Su Geun, Park Ik Jae, Lee Sol A, Yang Jin Wook, Lee Tae Hyung, Sohn Woonbae, Kim Jin Young, Jang Ho Won
Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea.
Department of Applied Physics, Sookmyung Women's University, Seoul, 04310, Republic of Korea.
Small. 2021 Oct;17(39):e2103457. doi: 10.1002/smll.202103457. Epub 2021 Aug 28.
To construct a highly efficient photoelectrochemical tandem device with silicon photocathode operating in alkaline conditions, it is desirable to develop stable and active catalysts which enable the photocathode to reliably perform under an alkaline environment. With nanostructured passivation layer and edge-exposed transition metal disulfides, silicon photocathode provides new opportunities for achieving unbiased alkaline solar water splitting. Here, the TiO nanorod arrays decorated by edge-rich MoS nanoplates are elaborately synthesized and deposited on p-Si. The vertically aligned TiO nanorods fully stabilize the Si surface and improve anti-reflectance. Moreover, MoS nanoplates with exposed edge sites provide catalytically active regions resulting in the kinetically favored hydrogen evolution under an alkaline environment. Interfacial energy band bending between p-Si and catalyst layers facilitates the transport of photogenerated electrons under steady-state illumination. Consequently, the MoS nanoplates/TiO nanorods/p-Si photocathode exhibits significantly improved photoelectrochemical-hydrogen evolution reaction (PEC-HER) performance in alkaline media with a high photocurrent density of 10 mA cm at 0 V versus RHE and high stability. By integrating rationally designed photocathode with earth-abundant Fe (NiCo) Cr anode and perovskite/Si tandem photovoltaic cell, an unassisted alkaline solar water splitting is accomplished with a current density of 5.4 mA cm corresponding to 6.6% solar-to-hydrogen efficiency, which is the highest among p-Si photocathodes.
为了构建一种在碱性条件下运行的具有硅光电阴极的高效光电化学串联装置，开发稳定且活性高的催化剂以使光电阴极在碱性环境下可靠运行是很有必要的。借助纳米结构钝化层和边缘暴露的过渡金属二硫化物，硅光电阴极为实现无偏压碱性太阳能水分解提供了新机遇。在此，精心合成了由富含边缘的MoS纳米片装饰的TiO纳米棒阵列，并将其沉积在p型硅上。垂直排列的TiO纳米棒充分稳定了硅表面并提高了抗反射性能。此外，具有暴露边缘位点的MoS纳米片提供了催化活性区域，导致在碱性环境下析氢动力学更有利。p型硅与催化剂层之间的界面能带弯曲促进了稳态光照下光生电子的传输。因此，MoS纳米片/TiO纳米棒/p型硅光电阴极在碱性介质中表现出显著改善的光电化学析氢反应（PEC-HER）性能，在相对于可逆氢电极（RHE）为0 V时具有10 mA cm的高光电流密度和高稳定性。通过将合理设计的光电阴极与储量丰富的Fe（NiCo）Cr阳极和钙钛矿/硅串联光伏电池进行合理集成，实现了无辅助碱性太阳能水分解，电流密度为5.4 mA cm，对应6.6%的太阳能制氢效率，这在p型硅光电阴极中是最高的。
