Uncontrolled emission of carbon dioxide (CO₂) from various industries, which poses a severe threat to the environment and induces climate change, CO₂ electroreduction is an advanced technology for converting waste CO₂ and closing anthropogenic carbon cycle. However, developing novel, affordable and high-performance electrocatalysts for converting CO₂ to value-added hydrocarbons remains highly challenging. Herein, a carbon dots-decorated, N-doped hierarchical biocarbon material is developed from municipal sludge, which can work as an effective and robust carbocatalyst for the electrochemical reduction of CO₂. More importantly, such hierarchical biocarbon catalyzes the electrochemical conversion of CO₂ to value-added organic products, including methane, methanol and ethanol, with excellent stability and total Faraday efficiency of 90.14% at about -0.71 V vs. RHE. Reasons for the carbocatalyst electroactivity toward efficient and selective production of ethanol is proposed to be the carbon dots and the doped N sites (especially pyridinic-N and pyrrolic-N), which is also validated by density functional theory calculations (DFT). A possible route for the electrochemical reduction of CO₂ is also unraveled. This study is a significant step forward to the exploitation of biomass wastes for harvesting greenhouse gasses and electrochemical energy conversion.

各行各业无节制地排放二氧化碳(CO ₂ )，对环境构成严重威胁并诱发气候变化，CO ₂电还原是一种转化废CO ₂和关闭人为碳循环的先进技术。然而，开发用于将 CO ₂转化为具有附加值的碳氢化合物的新型、负担得起的高性能电催化剂仍然极具挑战性。在此，从城市污泥中开发出一种碳点装饰的、N 掺杂的分级生物碳材料，它可以作为一种有效且稳健的碳催化剂用于 CO ₂的电化学还原。更重要的是，这种分级生物碳催化了 CO 的电化学转化₂到增值有机产品，包括甲烷、甲醇和乙醇，具有出色的稳定性和 90.14% 的总法拉第效率，在约 -0.71 V 与. RHE。碳点和掺杂的 N 位点（尤其是吡啶-N 和吡咯-N）是碳催化剂对乙醇高效和选择性生产的电活性的原因，这也通过密度泛函理论计算 (DFT) 进行了验证。电化学还原 CO _{2 的}可能途径也已揭开。这项研究是朝着利用生物质废物收集温室气体和电化学能量转换迈出的重要一步。