Single-Atom Ru in CoFe-LDH Drives Efficient Charge Separation on BiVO₄ for Solar Water Splitting

Bismuth vanadate (BiVO₄) is regarded as a promising photoanode for photoelectrochemical (PEC) water splitting. Despite its advantage in band gap and visible-light response, the BiVO₄ exhibits an unsatisfactory achieving water splitting due to severe charge recombination. Herein, we elucidate an innovative approach involving the incorporation of single Ru atom with a CoFe-LDH cocatalyst (Ru_0.51-CoFe-LDH) and integrating it onto the BiVO₄ semiconductor substrate. The resulting Ru_0.51-CoFe-LDH/BiVO₄ photoanode film demonstrates commendable charge injection efficiency (76%) and charge collection efficiency (100%). Interestingly, the yield of hydrogen and oxygen increases linearly at a stoichiometric ratio of about 2:1, reaching 158.6 and 67.4 μmol after 140 min of irradiation, respectively. According to experimental characterization and density functional theory calculation, this remarkable performance results from single Ru atoms triggering the electron rearrangement of Ru_0.51-CoFe-LDH to engineer active sites and optimize interfacial energetics. Additionally, the negative shift of Ru_0.51-CoFe-LDH band edge gives rise to more conspicuous band bending of the n-n junction formed with BiVO₄, expediting the separation and transfer of photogenerated electron-hole pairs at the interface. This work furnishes a new preparation perspective for PEC water splitting systems to construct single atoms in the semiconductor substrate.