Fine-tuning d-p hybridization in Ni-B_x cocatalyst for enhanced photocatalytic H₂ production

The H₂-evolution kinetics play a pivotal role in governing the photocatalytic hydrogen-evolution process. However, achieving precise regulation of the H-adsorption and H-desorption equilibrium (H_ads/H_des) still remains a great challenge. Herein, we propose a fine-tuning d-p hybridization strategy to precisely optimize the H_ads/H_des kinetics in a Ni-B_x modified CdS photocatalyst (Ni-B_x/CdS). X-ray absorption fine-structure spectroscopy and theoretical calculations reveal that increasing B-atom amount in the Ni-B_x cocatalyst gradually strengthens the d-p orbital interaction between Ni_3d and B_2p, resulting in a consecutive d-band broadening and controllable d-band center on Ni active sites. The above consecutive d-band optimization allows for precise modulation of the H_ads/H_des dynamics in the Ni-B_x/CdS, ultimately demonstrating a remarkable H₂-evolution activity of 13.4 mmol g^-1 h^-1 (AQE = 56.1 %). The femtosecond transient absorption spectroscopy further confirms the rapid electron-transfer dynamics in the Ni-B_x/CdS photocatalyst. This work provides insights into the optimal design of prospective H₂-evolution catalysts.