Ti3C2Tx ( T 1/4 F, OH) MXene nanosheets: conductive 2D catalysts for ambient electrohydrogenation of N2 to NH3+

The Haber-Bosch process for industrial-scale NH3 production suffers from high energy consumption and serious CO2 emission. Electrochemical N-2 reduction is an attractive carbon-neutral alternative for NH3 synthesis but is severely restricted due to N-2 activation needing efficient electrocatalysts for the N-2 reduction reaction (NRR) under ambient conditions. Here, we report that Ti3C2Tx (T = F, OH) MXene nanosheets act as high-performance 2D NRR electrocatalysts for ambient N-2-to-NH3 conversion with excellent selectivity. In 0.1 M HCl, such catalysts achieve a large NH3 yield of 20.4 mu g h(-1) mg(cat.)(-1) and a high faradic efficiency of 9.3% at -0.4 V vs. reversible hydrogen electrode, with high electrochemical and structural stability. Density functional theory calculations reveal that N-2 chemisorbed on Ti3C2Tx experiences elongation/weakness of the N?N triple bond facilitating its catalytic conversion to NH3 and the distal NRR mechanism is more favorable with the final reaction of *NH2 to NH3 as the rate-limiting step.