4 Optimization methods
From the above progresses, the reported N-doped carbon electrocatalysts containing Ni NPs, Ni single atoms and both have shown high ECR activity. Regrettably, the performance of Ni-N-C is difficult to meet the current practical goal. The catalytic activity and precise guidance of catalytic mechanisms need to be further developed and investigated. Therefore, in this section, we list the regulation strategies for promoting ECR activity and selectivity of Ni-N-C materials and discuss the relevant mechanisms.