As an emerging CO₂ conversion technology, the electrochemical CO₂ reduction (ECR) reaction has received widespread attention. For the ECR process, the accurate and rational design of electrocatalysts is essential and significant for improving the catalytic performance. Carbon-based materials are considered one of the promising electrocatalysts for ECR because of their variety of abundant sources, high specific surface area, high porosity, and multilevel dimensionality and tunable active sites. Furthermore, doping by heteroatoms and introducing metal atoms in the frameworks or substrates of the carbon materials are effective strategies for further improving the ECR activity. Particularly, nickel-nitrogen-carbon (Ni-N-C) materials show excellent reactivities for the ECR to CO and have the potential for large-scale applications. We summarize the recent development of Ni-N-C catalysts with a multilevel structure for the ECR to CO and also the key principles and primary parameters of the ECR. Furthermore, the rational and precise design of multilevel Ni-N-C catalysts on different carbon frameworks or substrates is discussed and presented, especially including carbon quantum dots, one dimensional (1D) carbon-based materials, two dimensional (2D) carbon-based materials and nanoporous carbon-based materials. The effects of microstructure on ECR performance are also analyzed. Finally, the challenges and outlook for Ni-N-C catalysts in an ECR system are presented. This review provides some new insights and guidelines for rationally designing and preparing Ni-N-C catalysts with a multilevel structure and high performance.

作为一种新兴的CO ₂转化技术，电化学CO ₂还原（ECR）反应已引起广泛关注。对于ECR工艺，电催化剂的准确合理的设计对于提高催化性能至关重要。碳基材料因其丰富的来源，高的比表面积，高的孔隙率，多维度的尺寸和可调节的活性位点等多种原因而被认为是ECR的有前途的电催化剂之一。此外，通过杂原子掺杂并在碳材料的骨架或基底中引入金属原子是进一步提高ECR活性的有效策略。特别是，镍-氮-碳（Ni-NC）材料对ECR转化为CO表现出出色的反应性，并具有大规模应用的潜力。我们总结了具有多级结构的ECR转化为CO的Ni-NC催化剂的最新进展，以及ECR的关键原理和主要参数。此外，还讨论并介绍了在不同碳骨架或基材上合理设计的多级Ni-NC催化剂，尤其包括碳量子点，一维（1D）碳基材料，二维（2D）碳基材料和纳米多孔碳基材料。还分析了微观结构对ECR性能的影响。最后，介绍了ECR系统中Ni-NC催化剂的挑战和前景。这篇综述为合理设计和制备具有多级结构和高性能的Ni-NC催化剂提供了一些新的见解和指南。