Performance analysis of a novel unassisted photoelectrochemical water splitting hybrid system based on spectral beam splitting

Abstract

Photoelectrochemical (PEC) water splitting, particularly self-biased PEC systems, holds great promise for solar energy utilization. However, the limited transparency of most photoelectrodes presents challenges in fabricating tandem photoelectrodes with photovoltaic (PV) cells for self-biased water splitting. Herein, a novel self-biased hybrid system integrating photoelectrodes (TiO₂, BiVO₄), beam splitters (BSs), and PV cell was proposed to enhance solar energy utilization and PEC water splitting performance. The results indicate that the integration of BSs significantly improves the current densities of both self-biased PV-PEC systems and single PEC systems. The current density of self-biased water splitting system with BSs exceeds that of the conventional TiO₂ + BVO-PV system, and the intersection point of the I–V curves for the photoanodes and solar cell is closer to the maximum power output of the solar cell. The effective utilization of the solar spectrum by both the photoelectrode and the PV cell in the hybrid system with BSs significantly increases the power output by a factor of 18.8 compared to the conventional tandem self-biased system. The predicted results indicate that the hydrogen production rate of the system with BSs is 12.1 µmol/(h·cm²), while the STH efficiency is enhanced by a factor of 12.38 and 19.87 compared to conventional TiO₂ + BVO-PV and TiO₂/BVO-PV tandem PV-PEC systems, respectively, demonstrating the advantage of the water splitting system with spectral BSs. In conclusion, this work provides an innovative approach of achieving self-biased water splitting by coupling spectral BSs with a PV-PEC system, resulting in improved solar energy harvesting efficiency.