“…Transition metal compounds, such as metal oxides (CoO x , FeO x , and CuO x ) (Ling et al, 2017;Suryanto et al, 2019;Zhang et al, 2021), sulfides (MoS x and CuS x ) (Guo et al, 2019a;Aslan et al, 2019;Yang et al, 2021), phosphides (CoP x and WP x ) (Du et al, 2018;Liu et al, 2021;Zhao et al, 2021), nitrides (MoN x and CoN x ) (Jin et al, 2018;Peng et al, 2019;Shu et al, 2020), carbides (Ni 3 C and Mo 2 C) (Li et al, 2016;Gao et al, 2019;Lu et al, 2019;Ma et al, 2020), and metal-nitride-carbide (M-N-C, M = Fe, Co, Ni, etc.) (Liu et al, 2017;Roy et al, 2018;Jin et al, 2019;Shi et al, 2020), have gradually attracted attention in electrocatalytic hydrogen production applications (Dinh et al, 2019).…”