Rational Engineering of Photocathodes for Hydrogen Production: Heterostructure, Dye-Sensitized, Perovskite, and Tandem Cells

Abstract

The use of renewable energy to generate hydrogen (H2) via photoelectrochemical (PEC) water splitting is an auspicious approach. In PEC, cathode electrode leads to a half-cell hydrogen evolution reaction (HER), and anode electrode leads to a half-cell oxygen evolution reaction (OER). In a PEC device, there are two important components: (i) light-absorbing electrode that generates electron-hole sets upon light incident and (ii) a catalyst that decreases the overpotential for H2 production and facilitates charge transfer. In this review, we focused on photocathode fabrication for H2 evolution. The photocathode materials are intensively investigated such as metal alloys, metal oxides, chalcogenides, borides, nitrides, and phosphides. In addition to this heterostructure, dye-sensitized and perovskite-sensitized photocathodes are developed. The tandem devices have been investigated to achieve high light absorption using two absorbers and optimizing different bandgap electrodes to get high solar to hydrogen conversion efficiency (STH). This review explores progress toward photocathode, with special prominence deployment in PEC systems, their importance, and the challenges in developing devices.