Tailoring doping locations and types for high‐performance CuFeO₂‐based photocatalysts

Abstract

Doping engineering has been recognized as an effective strategy for improving the solar‐to‐hydrogen conversion efficiency of delafossite CuFeO₂‐based photocatalysts. However, a comprehensive and systematic study on the doping effect in CuFeO₂ is still needed to establish a universal law. To address this, we utilized density functional theory calculations to scrutinize the doping effects of various dopants at different lattice positions. Our findings revealed that Mn replacing Fe and N replacing O are the most readily achievable doping methods under oxygen‐rich and oxygen‐poor conditions, respectively, with a maximum doping concentration of 10²⁰ cm⁻³ achievable at 900 K. Interestingly, we found that doping with N for O, F for O, and Ni for Cu generates impurity levels capable of capturing photogenerated holes at the top of the valence band, while Zn for Cu and Co for Fe engender impurity levels capable of capturing photogenerated electrons at the bottom of the conduction band, thereby facilitating the separation of photogenerated electron–hole pairs. However, it is worth highlighting that Mn replacing Fe results in impurity levels forming in the middle of the bandgap, acting as a recombination center for photogenerated electron–hole pairs. Furthermore, we discovered that Mg replacing Cu or Fe serves as an example of heterovalent doping capable of promoting the solar‐to‐hydrogen conversion efficiency of CuFeO₂. In isovalent doping, dopants with more valence electrons than Cu, dopants with the same valence electron as Fe, and dopants with less valence electron than O can enhance the solar‐to‐hydrogen conversion efficiency of CuFeO₂. Overall, this study provides a systematic analysis of the doping effects on CuFeO₂‐based photocatalysts and can be applied to doping engineering of ABO₂‐type delafossite photocatalytic materials.