Parametric study of biocathodes in microbial electrosynthesis for CO2 reduction to CH4 with a direct electron transfer pathway

Microbial electrosynthesis is a biocathode-driven device for chemicals production from carbon dioxide reduction and has been a promising carbon-consuming technology to alleviate the greenhouse effect and acquire the renewable energy. However, previous studies primarily focused on the effect of the operating parameters on the biocathode with an indirect electron transfer (IDET) pathway instead of a direct electron transfer (DET) pathway for CO2 reduction. In this work, we aim to study the effect of the operating parameters, including temperature, inorganic carbon source, and initial pH value, on the biocathode with a DET pathway for CO2 reduction to CH4. The CH4-producing biocathodes showed the respective optimum performance at the condition of 35 °C temperature, 4 g L−1 bicarbonate concentration, and pH 7.5 catholyte. This work provides an important guidance for the operation and development of microbial electrosynthesis for CO2 reduction to chemicals.