Flow Photoelectrochemical Devices for Converting Carbon from the Ocean

The capture and utilization of the dissolved inorganic carbon in seawater, i.e., 2 mM bicarbonates, offer an appealing approach to mitigate environmental concerns and advance the realization of a carbon-neutral society. Unbiased solar-driven photoelectrochemical (PEC) CO₂ reduction leads to sustainable production of chemicals and fuels. However, the development of reactors for unbiased PEC CO₂ capture and in-situ utilization in seawater has been scarcely reported, due to the lack of reactors that elegantly balance mass transfer and flow field design with PEC CO₂ reduction. We effectively achieve protons transportation and sequent in-situ conversion of freshly generated CO₂. We will describe the design and realization of 3D-printed reactors for unbiased PEC CO₂ capture and in-situ conversion in seawater, in which the locally generated CO₂ at BiVO₄ photoanodes can be brought to the neighboring Si photocathodes for CO₂ reduction reaction by optimized flow field, reducing the protons transfer distance and improving the local CO2 concentration on the surface of Si photocathodes. With this, we achieved excellent CO₂ capture velocity and outstanding solar to fuels (STF) efficiency of 0.71%: CO selectivity was increased from 3 to 19% compared with the conventional “artificial leaf” configuration of back-to-back photoanodes and photocathodes. A flowing reactor module is demonstrated for realistic ocean operation.