Built-in Electric Fields Enhancing Photocarrier Separation and H2 Evolution

The construct of the internal electric field (IEF) is recognized as an effective driver for promoting charge migration and separation to enhance photocatalytic performance. In this study, onedimensional nanorods of Mn 0.2 Cd 0.8 S (MCS) co-doped with interstitial chlorine (Clint) and substitutional chlorine (Clsub) were designed and synthesized using a one-step solvothermal method. The incorporation of Cl int and Cl sub led to an unbalanced charge distribution and the formation of IEF in the MCS nanorods, contributing to the improvement of photogenerated carrier kinetic behavior. Through density functional theory (DFT) calculations, the effect of Cl int and Cl sub doping on the activity of the MCS was visually explained by examining differences in electronic structure, charge distribution and H2 adsorption/desorption balance. Interestingly, the modulation of the energy band structure of MCS primarily resulted from the contribution of Clint, while Cl sub playing a negligible role. Moreover, the Cl sub further facilitated the optimization of Cl int concerning the H2 adsorption-desorption Gibbs free energy (Delta GH*) of MCS. Ultimately, the Delta GH* of 0.9 Cl-MCS favored H2 production (1.14 vs. 0.17 eV), leading to a 9 times increase in photocatalytic H2 production activity compared to MCS. This investigation presents a valuable approach for constructing IEF in bimetallic sulfide photocatalysts.