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 CuCrO2 as a p-type semiconductor has enabled H-2 generation through the coassembly of catalyst and dye components. Here, we present a CuCrO2 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-CuCrO2 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 mu A cm(-2) and generated 160 +/- 24 nmol of H-2 cm(-2), whereas the PMI-P-based photocathodes displayed higher photocurrents of -25 mu A 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, lambda > 420 nm, 25 degrees 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-CuCrO2 electrodes as well as the important role of the molecular dye structure in DSPEC fuel synthesis.