Gas phase photofuel cell consisting of WO3- and TiO2-photoanodes and an air-exposed cathode for simultaneous air purification and electricity generation

[Display omitted] •An autonomous, low-cost, widely and easily applicable photofuel cell is presented.•Simultaneous degradation of gaseous waste is coupled to sustainable electricity production.•Most promising results for application of WO3 in all-gas phase photofuel cell.•Driving parameters for direct photocatalysis and photoelectrochemistry identified.•Key performance indicators for all-gas-phase photofuel operation are determined. Research has shown the potential of photofuel cells (PFCs) for waste water treatment, enabling the (partial) recovery of the energy released from the degraded compounds as electricity. Literature on PFCs targeting air pollution on the other hand is extremely scarce. In this work an autonomously operating air purification device targeting sustainable electricity generation is presented. Knowledge on gas phase operation of PFCs was gathered by combining photocatalytic and photoelectrochemical measurements, both for TiO2 and WO3-based photocatalysts. While TiO2-based photocatalysts performed better in direct photocatalytic experiments, they were outperformed by WO3-based photoanodes in all-gas-phase PFC operation. Not only do WO3-based photocatalysts generate the highest steady state photocurrent, they also achieved the highest fuel-to-electricity conversion (>65 %). The discrepancies between gas phase photocatalytic and photoelectrochemical processes highlight the difference in driving material properties. This study serves as a proof-of-concept towards development of an autonomous, low-cost and widely applicable waste gas-to-electricity PFC device.