Facet engineering: Enhancing photogenerated carrier separation and transport in CuCoO2 photo(electro)catalysts

Efficient delafossite CuCoO2 photo(electro)catalysts necessitate effective separation and transport of photogenerated carriers to enable the production of solar fuel. Addressing this requirement, the current study employed facet engineering to induce the surface polarization effect. Hydrothermal conditions were utilized to prepare CuCoO2 photo(electro)catalysts with diverse morphologies and sizes. Specifically, CuCoO2 hexagonal nanosheets, predominantly exposing the (001) facet and possessing a thickness of 120 nm, exhibited optimal performance, as evidenced by a photocurrent density of 40 μA/cm2 under zero-bias conditions and 90 % degradation of tetracycline hydrochloride within 150 min. To overcome the limitations associated with hydrothermal preparation, Ca substitutional doping was employed. This doping strategy caused disruption of the O–Cu–O dumbbell-like structural motif, transforming CuCoO2 into an open-layered structure while simultaneously reducing the thickness of CuCoO2 hexagonal nanosheets to 30 nm. Consequently, an enhancement in the photo(electro)catalytic performance was achieved. By striking a balance between the surface polarization effect and the doping effect, CuCoO2 hexagonal nanosheets with 0.5 % Ca doping content and a thickness of 80 nm exhibited the most significant photo(electro)catalytic performance. This study presents a feasible strategy and concept for optimizing the morphology and hydrothermal preparation conditions of CuCoO2 nanomaterials, leading to improved photo(electro)catalytic performance.