Unveiling key impact parameters and mechanistic insights towards activated biochar performance for carbon dioxide reduction.

Chemically activated biochar is effective in supercapacitors and water splitting, but low conductivity hinders its application as a carbon support in carbon dioxide reduction reaction (CO ₂ RR). Based on the observed CO ₂ RR performance from potassium hydroxide (KOH)-activated biochar, increased microporosity was hypothesized to enhance the performance, leading to selection of potassium carbonate (K ₂ CO ₃ ) for activation. K ₂ CO ₃ activation at 600℃ increased microporosity significantly, yielding a total Faradaic efficiency of 72%, compared to 60% with KOH at 800℃. Further refinement of thermal ramping rate enriched micropore content, directly boosting FE _C to 82%. Additionally, K ₂ CO ₃ 's lower activation temperature could preserve hydroxyl groups to improve ethylene selectivity. These findings demonstrate that optimizing microporosity and surface chemistry is critical for designing activated biochar-based CO ₂ RR electrocatalysts. Despite lower electrical conductivity of activated biochar, selecting the appropriate activating agents and conditions can make it a viable alternative to carbon black-based electrocatalysts.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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