As a desirable alternative for oxygen evolution reaction (OER), urea oxidation reaction (UOR) with the effectively reduced overpotential has attracted considerable attention in pollutant degradation and rechargeable Zn-air battery (ZAB). Herein, a bifunctional electrocatalyst with CoNi alloy and Co–N dual active sites encapsulated by nitrogen-doped carbon nanotubes have been rationally designed and successfully prepared. The as-obtained catalyst CoNi/Co–NCNT displays excellent catalytic activity for oxygen reduction (ORR) and UOR with a narrow potential difference of 0.56 V. The urea-assisted rechargeable ZABs based on CoNi/Co–NCNT provide higher energy conversion efficiency (61%), 15% higher than that of conventional ZABs. In addition to verify the UOR pathway on the CoNi/Co–NCNT, DFT calculations reveal that CoNi alloy and Co–N in CoNi/Co–NCNT synergistically function as the main active sites for ORR and UOR. The excellent ORR catalytic performance and the superior energy conversion efficiency of CoNi/Co–NCNT based urea-assisted rechargeable ZAB is expected to accelerate the practical application of ZAB technology. This work paved a new way for the development of bifunctional catalysts for higher efficiency ZABs, and also provides a potential scheme for disposing urea rich wastewater.

中文翻译：

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Co 掺杂氮化碳纳米管封装 CoNi 合金作为尿素辅助可充电锌空气电池的双功能催化剂


作为析氧反应 （OER） 的理想替代品，有效降低过电位的尿素氧化反应 （UOR） 在污染物降解和可充电锌空气电池 （ZAB） 中引起了相当大的关注。在此，合理设计并成功制备了一种由氮掺杂碳纳米管封装的具有 CoNi 合金和 Co-N 双活性位点的双功能电催化剂。所获得的催化剂 CoNi/Co-NCNT 表现出优异的氧还原 （ORR） 和 UOR 催化活性，电位差仅为 0.56 V。基于 CoNi/Co-NCNT 的尿素辅助充电 ZAB 提供更高的能量转换效率 （61%），比传统 ZAB 高 15%。除了验证 CoNi/Co-NCNT 上的 UOR 途径外，DFT 计算还表明 CoNi/Co-NCNT 中的 CoNi 合金和 Co-N 协同作用，作为 ORR 和 UOR 的主要活性位点。基于 CoNi/Co-NCNT 的尿素辅助可充电 ZAB 优异的 ORR 催化性能和卓越的能量转换效率有望加速 ZAB 技术的实际应用。这项工作为开发用于更高效 ZAB 的双功能催化剂铺平了一条新道路，也为处理富含尿素的废水提供了一种潜在的方案。