A Scanning Probe Investigation of the Role of Surface Motifs in the Behavior of p-WSe(sub2) Photocathodes

Published

October 8, 2015

Author(s)

Jesus M. Velazquez, Jimmy John, Daniel V. Esposito, Adam Pieterick, Ragip Pala, Guofeng Sun, Xinghao Zhou, Zhuangqun Huang, Shane Ardo, Bruce S. Brunschwig, Nathan S. Lewis

Abstract

The spatial variation in the properties and performance of bare and Pt-decorated p-type WSe(sub2) photocathodes has been investigated by using Scaning Photocurrent Microscopy (SPCM) and Local Spectral Response in solution. Microscale SPCM measurements revealed significant differences in the charge-collection performance of different macroscopic terraces, and differences in the quality of the terraces rather than the effects of the macro-scale step edges dominated the charge-collection efficiency of the samples. Local topographic and spectral response measurements showed that the local electronic structures of terraces differed from one another. Local spectral response measurements indicated that the low-quality terraces showed sub-band-gap states that were not present in high-quality terraces. Hence, the performance of bulk single crystals of 2D layered p-WSe(sub2) photocathodes is dictated by the photoactivity of terraces and not by the charge collection properties of the macro-scale edge sites, as it has been widely understood formerly.

Citation

Energy and Environmental Science

Pub Type

Journals

Keywords

tungsten diselenide, photoelectrochemistry, scanning photocurrent microscopy

Citation

Velazquez, J. , John, J. , Esposito, D. , Pieterick, A. , Pala, R. , Sun, G. , Zhou, X. , Huang, Z. , Ardo, S. , Brunschwig, B. and Lewis, N. (2015), A Scanning Probe Investigation of the Role of Surface Motifs in the Behavior of p-WSe(sub2) Photocathodes, Energy and Environmental Science (Accessed July 21, 2024)