Energy loss analysis in photoelectrochemical water splitting: A case study of hematite photoanodes

Insightful understanding of the energy loss mechanism during photoelectrochemical (PEC) processes is of vital importance for efficient solar fuel production. Potential-current features under light illumination are typically used to evaluate the effectiveness of the PEC processes. However, energy loss that leads to various shapes of measured photocurrent-potential (j-E) curves is still not well understood. Herein, based on hematite photoanodes, we systematically studied the photocurrent-potential-light intensity (j-E-I) relationships to acquire quantitative understanding of the loss mechanism during the PEC process by decoupling it into a photovoltaic (PV) and an electrocatalytic (EC) process. Both numerical simulation and experimental results have confirmed the reasonability of this analysis method. It provides comprehensive understanding of the energy loss at the semiconductor-electrolyte junction and the surface electrocatalysis process for further optimizing the PEC solar energy conversion process.