Boosting Carbon Dioxide Reduction in a Photocatalytic Fuel Cell with a Bubbling Fluidized Cathode: Dual Function of Titanium Carbide.

Photoelectrochemical reduction of carbon dioxide (CO 2 ) is a promising avenue to realize resourceful utilization of carbon dioxide and mitigate the energy shortage. Herein, a photocatalytic fuel cell with a bubbling fluidized cathode (PFC-BFC) is proposed to increase the performance of the photocatalytic CO 2 reduction reaction (CO 2 RR). Titanium carbide (Ti 3 C 2 ) is first used as a fluidized cathode catalyst with the dual features of superior capacitance and high CO 2 RR catalytic activity. Compared with the conventional PFC system, the as-proposed PFC-BFC system exhibits a higher gas production performance. Particularly, the generation rate and Faraday efficiency for CH 4 production reach to 37.2 μmol g -1 h -1 and 72%, which are 10.9 and 6.5 times higher than that of the conventional PFC system, respectively. The bubbling fluidized cathode allows a rapid electron transfer between catalysts and the current collector and an efficient diffusion of catalysts in the whole solution, thus remarkably increasing the effective reaction area of the CO 2 RR. In addition, the fluidized reaction mechanism of charging/discharging-coupled CO 2 RR is investigated. Significantly, a magnified PFC-BFC system is designed and exhibits a similar gas generation rate compared to that of the small-scale system, indicating a good potential of scaling up in the industry applications. These results demonstrated that the proposed PFC-BFC system can maximize the utilization of catalyst active sites and enhance the reaction kinetics, providing an alternative design for the application of CO 2 RR.