Electrochemical reduction of CO₂ to syngas (CO and H₂) offers an efficient way to mitigate carbon emissions and store intermittent renewable energy in chemicals. Herein, the hierarchical one-dimensional/three-dimensional nitrogen-doped porous carbon (1D/3D NPC) is prepared by carbonizing the composite of Zn-MOF-74 crystals in situ grown on a commercial melamine sponge (MS), for electrochemical CO₂ reduction reaction (CO₂RR). The 1D/3D NPC exhibits a high CO/H₂ ratio (5.06) and CO yield (31 mmol g⁻¹ h⁻¹) at −0.55 V, which are 13.7 times and 21.4 times those of 1D porous carbon (derived from Zn-MOF-74) and N-doped carbon (carbonized by MS), respectively. This is attributed to the unique spatial environment of 1D/3D NPC, which increases the adsorption capacity of CO₂ and promotes electron transfer from the 3D N-doped carbon framework to 1D carbon, improving the reaction kinetics of CO₂RR. Experimental results and charge density difference plots indicate that the active site of CO₂RR is the positively charged carbon atom adjacent to graphitic N on 1D carbon and the active site of HER is the pyridinic N on 1D carbon. The presence of pyridinic N and pyrrolic N reduces the number of electron transfer, decreasing the reaction kinetics and the activity of CO₂RR. The CO/H₂ ratio is related to the distribution of N species and the specific surface area, which are determined by the degree of spatial confinement effect. The CO/H₂ ratios can be regulated by adjusting the carbonization temperature to adjust the degree of spatial confinement effect. Given the low cost of feedstock and easy strategy, 1D/3D NPC catalysts have great potential for industrial application.

中文翻译：

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MOF 衍生的 1D/3D N 掺杂多孔碳，用于空间受限电化学 CO2 还原为可调节合成气

_{将CO 2}电化学还原为合成气（CO 和H ₂）提供了一种有效的方法来减少碳排放并在化学品中存储间歇性可再生能源。在此，通过碳化在商用三聚氰胺海绵（MS）上原位生长的 Zn-MOF-74 晶体复合材料，制备了多级一维/三维氮掺杂多孔碳（1D/3D NPC），用于电化学 CO2 ₂还原反应(CO ₂ RR)。1D/3D NPC在-0.55 V下表现出高CO/H ₂比（5.06）和CO产率（31 mmol g ^-1  h ^-1），分别是1D多孔碳（源自Zn）的13.7倍和21.4倍。 -MOF-74）和N掺杂碳（通过MS碳化），分别。这归因于1D/3D NPC独特的空间环境，增加了CO ₂的吸附能力，促进电子从3D N掺杂碳骨架到1D碳的转移，改善了CO ₂ RR的反应动力学。实验结果和电荷密度差图表明CO ₂ RR的活性位点是一维碳上与石墨N相邻的带正电的碳原子，HER的活性位点是一维碳上的吡啶N。_{吡啶N和吡咯N的存在减少了电子转移的数量，降低了反应动力学和CO 2} RR的活性。CO/H ₂比值与N物种的分布和比表面积有关，而N物种的分布和比表面积由空间限制效应的程度决定。CO/H ₂比率可以通过调节碳化温度来调节空间限制效应的程度。鉴于原料成本低廉且策略简单，1D/3D NPC催化剂具有巨大的工业应用潜力。