“…As such, we studied the adsorption of Mn, Fe, Co, and Ni, and the post-adsorbed structures are referred as A-g-C 3 N 4 /C 2 N- h 2D (A = Mn, Fe, Co, Ni) nanoribbons. 47 First, we take the adsorption of Mn as an example to prove the position where the adsorption is most stable. There are two transition metal adsorption sites, as shown in Fig.…”