Ni/N co-doped NH2-MIL-88(Fe) derived porous carbon as an efficient electrocatalyst for methanol and water co-electrolysis

Abstract

The technology of using electricity generated from renewable energy sources such as wind and solar power for water electrolysis to produce hydrogen has achieved high efficiency, high purity, and environmental friendliness. However, its further development is constrained by the high overpotential of the oxygen evolution reaction (OER) and the high cost of precious metal catalysts. The methanol oxidation reaction (MOR) as an alternative to OER can significantly reduce overall energy consumption and accelerate the hydrogen evolution reaction. This study innovatively utilizes the metal-organic framework (MOF) of NH₂-MIL-88(Fe) to introduce Ni doping, preparing a series of Fe_xNi_y-MOF and their bimetallic carbon derivatives (Fe_xNi_y/C) through solvothermal synthesis and high-temperature carbonization. Results show that FeNi₂/C exhibited excellent performance in OER, with a Tafel slope of 38.69 mV·dec⁻¹ and an overpotential of 335 mV at 10 mA cm⁻², comparable to RuO₂. In MOR, the overpotential was 193 mV, reduced by approximately 140 mV compared to OER, with outstanding stability. The catalytic mechanism was analyzed using ion chromatography, revealing the key role of Ni doping in enhancing catalytic activity and stability. This study provides new strategies for improving the electrocatalytic hydrogen production efficiency of renewable energy and reducing the production cost of hydrogen energy.