Efficient Water Oxidation Using Ta 3 N 5 Thin Film Photoelectrodes Prepared on Insulating Transparent Substrates

Photoelectrochemical (PEC) water splitting using visible‐light‐responsive photoelectrodes is the preferred approach to converting solar energy into hydrogen as a renewable energy source. A transparent Ta 3 N 5 photoanode embedded within a PEC cell having a tandem configuration is a promising configuration that may provide a high solar‐to‐hydrogen energy conversion efficiency. Ta 3 N 5 thin films are typically prepared by heating precursor films in an NH 3 flow at high temperatures, which tends to degrade the transparent conductive layer, such that producing efficient Ta 3 N 5 transparent photoanodes is challenging. Herein, the direct preparation of transparent Ta 3 N 5 photoanodes on insulating quartz substrates was demonstrated without the insertion of a transparent conductive layer. The resulting devices generated a photocurrent of 6.0 mA cm −2 at 1.23 V vs. a reversible hydrogen electrode under simulated sunlight. This study provides a new strategy for the preparation of transparent photoelectrodes that mitigates current challenges.