Advanced Electrocatalytic Performance of NiMo-Engineered Ti3C2Tx MXene for Sustainable Hydrogen Generation from Wastewater

Abstract

Electrocatalytic wastewater splitting presents a viable alternative to alleviating the strain on freshwater resources traditionally used for hydrogen production. The critical challenge lies in developing a robust multifunctional catalyst capable of operating efficiently in a wastewater environment. MXenes─transition-metal carbides, nitrides, and carbonitrides─have emerged as potent electrocatalysts for hydrogen generation, attributed to their abundant surface functionalities and active basal planes. However, their performance and stability under wastewater conditions remain unexplored. Given the high organic load in wastewater, MXene engineering at the interface is imperative to ensure stability. This study pioneers the engineering of Ti₃C₂T_x with transition-metal alloys to create a hybrid NiMo/Ti₃C₂ electrocatalyst, evaluated for hydrogen evolution in simulated wastewater (1 M KOH with 5 ppm methylene blue). The NiMo/Ti₃C₂ catalyst was synthesized through dip-coating Ti₃C₂T_x onto Ni foam, followed by optimized NiMo electrodeposition. The catalyst exhibited an overpotential of 45.8 mV at 10 mA/cm² in simulated wastewater and demonstrated prolonged stability at elevated current densities of 50 and 100 mA/cm². Additionally, it achieved approximately 82% degradation of MB within 90 min and a hydrogen production rate of 0.361 mmol/h. In real wastewater samples, the engineered Ti₃C₂T_x showcased significant reductions in chemical oxygen demand, total organic carbon, and turbidity, with a hydrogen production rate of 0.327 mmol/h. Ti₃C₂T_x MXene provides a larger surface area and active basal planes for the adsorption of ions, and NiMo alloy acts as a charge transporter in the HER. These results highlight the potential of the interface-engineered Ti₃C₂T_x system as a multifunctional electrocatalyst for concurrent wastewater treatment and hydrogen production.