Defect Passivation of Mn²⁺-Doped CsPbX₃(X=Cl,Br) Perovskite Nanocrystals as Electrocatalyst for Overall Water...

Mn doping has been used to improve the physical chemistry of lead halide perovskite nanocrystals such as CsPbX₃, where X is a halogen ion. In this paper, a two-phase method for Mn-doped CsPbX₃ nanosheets (where X=Br, Cl), namely water-hexane system, is reported. Compared to conventional catalyst arrays, the band gap of CsPbBr₃ nanocrystalline is easily tuned, the carrier diffusion distance is remote, the band edge position of the band structure is favorable for a wide range of electrocatalytic redox reactions, and the catalytic active site is maximally exposed, providing a larger electrolyte contact area. The porous hierarchical structure also accelerates the release of hydrogen bubbles. The results showed that the optimized Mn : CsPbBr₃ catalyst exhibited excellent electrolytic performance of aquatic hydrogen in alkaline electrolyte (1 mol/L KOH). The overpotentials of the oxygen evolution reaction (OER) at the current densities of 10 and 100 mA cm^-2 are only 114.4 and 505.4 mV, respectively, with a Tafel slope of 43 mV dec^-1. At a current density of 10 mA cm^-2, the excess potential required for the hydrogen evolution reaction (HER) is 158.6 mV and it exhibits excellent electrochemical stability. The Mn : CsPbBr₃ nanocrystalline consists of two electrodes for hydrolysis of water, requiring only a voltage of 1.45 V. This provides implications for the optimization of electrocatalysts in alkaline electrolytes with the aim of developing next generation 2D electrocatalysts for overall water splitting.