Acetate production from inorganic carbon (HCO3-) in photo-assisted biocathode microbial electrosynthesis systems using WO3/MoO3/g-C3N4 heterojunctions and Serratia marcescens species

The efficient production of acetate from HCO3- is demonstrated in a photo-assisted microbial electrosynthesis system (MES) incorporating a WO3 /MoO3/g-C3N4 heterojunction photo-assisted biocathode supporting Serratia marcescens Q1 electrotroph. The WO3 /MoO3/g-C3N4 structured electrode consisting of a layer of g-C3N4 coated on graphite felt decorated with W/Mo oxides nanoparticles exhibited stable photocurrents, 4.8 times higher than the g-C3N4 electrode and acetate production of 3.12 +/- 0.20 mM/d with a CEacetate of 73 +/- 4 % and current of 2.5 +/- 0.3 A/m(2). Photo-induced electrons on the conduction bands of WO3 /MoO3/g-C3N4 favoured hydrogen evolution, which was metabolized by S. marcescens with HCO3- to acetate, while the holes were refilled by the electrons travelling from the anode. Such mechanism reduced the interfacial resistances creating a supplementary driving force leading to higher acetate production. The biocompatible components of WO3 /MoO3/g-C3N4 synergistically couple light-harvesting and further catalyze S. marcescens to acetate from HCO3-, providing a feasible strategy for achieving sustainable high rates of acetate production.