Inverse Opal CuCrO2 Photocathodes for H2 Production Using Organic Dyes and a Molecular Ni Catalyst

Dye-sensitized photoelectrochemical (DSPEC) cells are an emerging approach to producing solar fuels. The recent development of delafossite CuCrO 2 as a p-type semiconductor has enabled H 2 generation through the coassembly of catalyst and dye components. Here, we present a CuCrO 2 electrode based on a high-surface-area inverse opal (IO) architecture with benchmark performance in DSPEC H 2 generation. Coimmobilization of a phosphonated diketopyrrolopyrrole ( DPP-P ) or perylene monoimide ( PMI-P ) dye with a phosphonated molecular Ni catalyst ( NiP ) demonstrates the ability of IO-CuCrO 2 to photogenerate H 2 . A positive photocurrent onset potential of approximately +0.8 V vs RHE was achieved with these photocathodes. The DPP-P -based photoelectrodes delivered photocurrents of -18 μA cm -2 and generated 160 ± 24 nmol of H 2 cm -2 , whereas the PMI-P -based photocathodes displayed higher photocurrents of -25 μA cm -2 and produced 215 ± 10 nmol of H 2 cm -2 at 0.0 V vs RHE over the course of 2 h under visible light illumination (100 mW cm -2 , AM 1.5G, λ > 420 nm, 25 °C). The high performance of the PMI-constructed system is attributed to the well-suited molecular structure and photophysical properties for p-type sensitization. These precious-metal-free photocathodes highlight the benefits of using bespoke IO-CuCrO 2 electrodes as well as the important role of the molecular dye structure in DSPEC fuel synthesis.