(596e) Novel Metal Carbide (MXene) Based Catalyst for Industrial-Scale Electrochemical Production of Hydrogen

Hydrogen (H2) is considered as the most promising clean energy source to replace conventional fossil fuels. Despite the exceptional catalytic activity of Pt-group metals, the high cost and relatively less durability of these noble metal-based catalysts remain one of the key bottlenecks for sustainable hydrogen production at the industrial scale. In this report, we synthesized a new type of 2D metal carbide (MXene). By loading metal onto the surface of MXene, we developed a highly effective and stable catalyst for alkaline hydrogen evolution reaction (HER). The optimized catalyst exhibited a small overpotential of 62.58 mV at 10 mA/cm2 and a low Tafel slope of 44.34 mV/dec. At high current density of 100 mA/cm2 and 1000 mA/cm2, the low overpotentials of 191.18 mV and 407.72 mV were achieved, significantly outperforming the commercial Pt/C electrode. Under both current ranges, our catalyst exhibited excellent stability as 500 h at 10 mA/cm2 and for 100 h at 1000 mA/cm2 without any obvious degradation. In flow cell tests, by pairing up with Ni Foam, our catalyst also required much lower cell voltage than commercial Ni Foam||Pt/C and maintained ~ 100% H2 faradic efficiency over the 15h continuous tests from 100 to 400 mA/cm2. X-ray absorption near edge structure demonstrated a temperature induced redistribution of metal on MXenes from single sites and large nanoparticles to uniform small nanoparticles. Density functional theory calculation, combined with X-ray photoelectron spectroscopy and Extended X-ray Absorption Fine Structure Spectroscopy, revealed that the HER activity was sensitive to the coordination environment of metal on MXene and the metal-carbide interface might be the active site for HER chemistry. This work sheds light on structure design and utilization of metal-support interaction (MSI) in MXene-supported metal catalysts for the efficient electrochemical water splitting at industrial scale.