Mn and N-codoped carbon materials (MnÀ NÀ C) have recently aroused enormous interest owing to their unique advantages over Fe-NÀ C counterparts. MnÀ NÀ C electroactive materials have been conveniently fabricated from a cationic Cd(II)-based MOF (CdÀ TTPBA-4(TTPBA-4 = N 1 ,N 1 ,N 4 ,N 4-tetrakis(4-(4H-1,2,4-triazol-4-yl)phenyl)benzene-1,4-di-amine) which can effectively and controllably achieve the Mn-doping through anion-exchange between the exterior MnO 4 À anions and its exchangeable ClO 4 À anions. The anion-exchanged materials of MnO 4 À @CdÀ TTPBA-4 were pyrolyzed at 1000°C followed by acid-washing and second heat-treatment to give MnÀ NÀ C electroactive materials with promising oxygen reduction activity. In the alkaline electrolyte, the optimal MnÀ NÀ C material exhibits an outstanding oxygen reduction activity with the onset potential of 0.93 V (vs RHE) and half-wave potential of 0.82 V (vs RHE), together with a good long-term stability.

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Metal-free carbon materials doped with multiple nonmetal heteroatoms (e. g. N, B, S, P) have emerged as a promising class of electrocatalysts toward oxygen reduction reaction (ORR). Herein, B, N-codoped carbon electrocatalysts are conveniently prepared by use of ZIF-8 precursor, which involves cageencapsulation of PhB(OH) 2 before high-temperature pyrolysis.By modulating the B-doping amount and pyrolysis temperature, an optimal B, N-codoped carbon electrocatalyst toward ORR is achieved, which shows ORR activity (E onset = 0.95 V, and E 1/2 = 0.83 V vs RHE) comparable to the Pt/C benchmark, with a good methanol tolerance and long-term stability.

Mn–N–C materials have received increasing interest in recent years because of their low Fenton reactivity and ORR activity comparable to those of their Fe–N–C and Co–N–C counterparts. In this contribution, an atomically dispersed Mn–N–C electrocatalyst with a prominent oxygen reduction performance was constructed by employing a cationic Cd-MOF as a precursor that can facilely and accurately introduce MnO4 – anions through anion exchange. The best-performing Mn–N–C catalyst displays a 0.96 V (vs RHE) E onset (onset potential) and a 0.87 V (vs RHE) E 1/2 (half-wave potential) in an alkaline solution, which exceed those of the benchmark Pt/C catalyst. In particular, the maximal power density of the self-made zinc-air battery reaches 200 mW·cm–2, surpassing that of most reported Mn–N–C materials.

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