“…In recent decades, transition metal-based compounds such as carbides [ 8 , 9 , 10 , 11 ], phosphides [ 12 , 13 , 14 ], sulfides [ 15 , 16 , 17 ], oxides [ 18 , 19 , 20 ], borides [ 21 , 22 , 23 ], and nitrides [ 24 , 25 , 26 ] have been reported to be used in the HER electrocatalysts and shown good catalytic performance. Among them, molybdenum carbide (Mo x C) has attracted extensive attention because of its different Mo valence, adjustable phase composition, high abundance, high chemical stability, and d-band electronic structure, which is similar to Pt-based catalysts [ 27 , 28 , 29 , 30 ].…”