Performance Optimization of Nickel-Doped CuCoO ₂ for Photoelectrocatalytic Water Splitting

Delafossite CuCoO₂ is a material with a unique quasi-two-dimensional layered structure and excellent physicochemical properties, holding the potential to become an efficient photocatalytic material. Its characteristics, such as being safe, nontoxic, inexpensive, and abundant in resources, make it highly favored. To further understand and enhance its photocatalytic performance, this study employed nickel doping to modify CuCoO₂. The results reveal that increasing the nickel doping content led to a reduction in the CuCoO₂ crystal thickness and a gradual narrowing of the band gap, reaching 2.29 eV with optimal doping. In photoelectrochemical tests, the 10% Ni-doped CuCoO₂ exhibited the best performance: under zero bias, it achieved a photocurrent density of 80 μA/cm², a 4-fold enhancement compared to undoped CuCoO₂, and required only 450 mV overpotential to sustain a current density of 100 mA/cm². Additionally, the incident photon-to-current efficiency (IPCE) was increased by 3.6× after doping. These quantitative results highlight the effectiveness of nickel doping in enhancing the optoelectronic properties and catalytic durability of CuCoO₂.