Polyoxymetalate liquid-catalyzed polyol fuel cell and the related photoelectrochemical reaction mechanism study

•A polyoxometalate-catalyzed fuel cell favored by long-chain polyols is fabricated.•The cell power density is dependent on the hydroxyl number of polyols.•The photoelectrochemical reaction mechanism of polyol fuel cell is revealed.

A novel design of liquid catalyzed fuel cell (LCFC), which uses polyoxometalates (POMs) as the photocatalyst and charge carrier has been reported previously. In this paper, the adaptability of biomass fuels (e.g., glycerol and glucose) to the LCFC and corresponding cell performance were studied in detail here. An interesting finding that greatly differs from conventional fuel cell is that high molecular weight fuels rather than small molecule fuels (e.g., methanol and ethylene glycol) are favored by the novel LCFC with respect to the power densities. The power output of LCFC strongly depends on the number and structure of hydroxyl groups in the biomass fuels. The evidence of UV–Vis and 1H NMR spectra shows that the preassociation between POM and alcohol fuels, which determines the photoelectrochemical reaction pathway of POM, is enhanced as the number of hydroxyl increases. Experimental results also demonstrate that more hydroxyl groups in the molecules lead to faster photoelectrochemical reaction between POM and fuels, higher reduction degree of POM, and further higher power output of LCFC. Our study reveals that biomass-based polyhydroxyl compounds such as starch, hemicellulose and cellulose are potential high-performance fuels for LCFC.

Graphical abstractA polyoxometalate liquid catalyzed fuel cell (LCFC) using biomass derivatives, such as glycerol and glucose, as the fuel under UV irradiation was fabricated and related photoelectrochemical reaction mechanism was studied.Figure optionsDownload full-size imageDownload as PowerPoint slide