Tailoring vinegar residue-derived all-carbon electrodes for efficient electrocatalytic carbon dioxide reduction to...

Electrocatalytic carbon dioxide reduction (ECO₂R) to formate is the most technically and economically feasible approach to achieve electrochemical CO₂ value addition. Here, a few-layer graphene is prepared from vinegar residue. Then a series of heteroatom-doped vertical graphene electrodes (X-rGO, X=P/S/N/B/, NS/NP/NB, NSP/NSB/NPB/NSPB) are prepared. The NS-rGO has improved ECO₂R to formate selectivity (Faraday Efficiency (FE_HCOO^-) = 78.7 %) thanks to the synergistic effect between N and S. Carbon quantum dots (CQDs) are introduced into the electrode, the doped heteroatoms are further removed by high-temperature to form the defects-rich electrode (NS-CQDs-rGO-1100), which has better catalytic performance (FE_HCOO^-=90 %, stability over 10 h) with electrochemical double layer capacitance of 12.5 mF cm^-2. The intrinsic effect of heteroatom doping and defects on the ECO₂R activity of the electrodes are explored by density functional theory calculation. This work broadens the field of preparation of graphene and opens the door to the development of cost-effective electrocatalysts for efficient ECO₂R.