Temperature Coefficients of Photoelectrochemistry: A Case Study of Hematite-Base Water Oxidation
Huiting Huang, Jun Wang, Minyue Zhao, Ningsi Zhang, Yingfei Hu, Jianyong Feng, Zhaosheng Li, Zhigang Zou
Abstract
The behavior of photoelectrochemical (PEC) water splitting under temperature is fundamentally important yet less investigated, because of the lack of a suitable analysis method to decouple and quantify the contributions of each elemental step (charge carrier generation and transport, photovoltage generation, and surface catalysis) to overall PEC efficiency. Herein, by using hematite as the prototype electrode, its performance dependence on temperature is well resolved, and the efficiency loss/gain of each elemental step during PEC water splitting is also quantitatively analyzed. The deteriorated temperature coefficient of open-circuit voltage on hematite for water oxidation (from −6.50 mV K–1 to −3.50 mV K–1) than sulfite oxidation (from −3.52 mV K–1 to −2.60 mV K–1) reveals that slow water oxidation kinetics retards photovoltage generation. The proposed analysis approach and fundamental understanding of the influences of each elemental step on the temperature coefficients would provide valuable insight into the future development and implementation of PEC devices.