(5g) A New System of Electrochemical Oxidation Conversion of Biomass Coupled with Electrochemical Reduction of Carbon Dioxide to Formic Acid

Biomass is the most abundant renewable resource in nature. The electrooxidation of biomass plays a key role in the process of converting biomass to value-added chemicals. Coupling biomass electrooxidation and electroreduction of carbon dioxide (CO₂RR) with renewable electricity is a meaningful way to achieve carbon negativity, produce high value-added products, and also reduce the energy consumption of traditional systems coupling with OER and CO₂RR.

Therefore, in this work, we developed a facile method of electrodeposition based on chelating agents for preparing two-dimensional nanosheet electrocatalysts on both the anode and cathode. The anode electrocatalyst is prepared using electrodeposition method assisted with different chelating agent. It was found that the Ni-based electrocatalyst prepared by using EDTA2Na had the best performance for electrooxidation of biomass derived aldehydes (e.g. 5-hydroxymethylfurfural (HMF)). When the ratio of Ni²⁺ to EDTA2Na is 1:0.25, the electrocatalyst is dispersed scaly structure, which can achieve a high yield of 96.2% for FDCA and 96.7% for FE_FDCA. The Ni-0.25EDTA2Na electrocatalyst can be stably cycled six time.

In the cathode, Bi-based electrocatalysts prepared by electrodeposition with different chelating agents have different morphologies. Bi-EDTA2Na has two-dimensional sheets with nano-corrugated paper morphology, which can achieve the FE_HCOO- of 96% and the current density of 60mA/cm². In the wide voltage range, the FE_HCOO- of Bi-EDTA2Na is greater than 90%. Bi-EDTA2Na can be stably cycled for 24h. The current density of CO₂RR to HCOOH can be further improved by using flow cell. And we prove BiO₂CO₃ is the active species.

Compared with the traditional OER-CO₂RR coupling system, the new system can reduce the energy by 7.02%. The value of FDCA produced by the anode HMFOR is greatly increased by hundreds of times compared with the traditional system of OER. This work developed a renewable electricity-driven new system of biomass electrooxidation coupled with CO₂RR.