Indium doping induces morphological and electronic structure optimization of nickel-thiophene-based metal-organic...

Modulating the intrinsic structure of metal-organic frameworks (MOFs) is considered as a useful strategy for achieving high-efficiency oxygen evolution reaction (OER). In this paper, we demonstrate the doping of nickel-thiophene metal organic framework (Ni-TDC) with the p-block metals indium (In) to modulate their microscopic morphology and electronic structure. The strong electronic coupling between metallic Ni and In boosts the electronic conductivity and facilitates the electron transfer, thus accelerating OER kinetics. Compared to the pristine Ni-TDC, the modified electrocatalyst requires only 227 mV to achieve 10 mA cm^-2, and it exhibits long-term stability, remaining active for 100 h without significant degradation. On this basis, an overall water electrolyzer assembled with NiIn_0.1-TDC as the anode and Pt/C as the cathode achieves a low voltage of only 1.49 V at 10 mA cm^-2 and can also operate stably for over 100 h. Density functional theory (DFT) calculations show that In doping causes the up-shift of d-band center of Ni and reduces the energy barrier of the rate-determining step of *OH → *O, and thus enhancing the OER performance. This work highlights the potential of p-block metal doping for the strategic design of advanced MOF electrocatalysts.