A highly efficient tungsten carbide catalyst for natural Photothermal-Driven formic acid dehydration reaction

Abstract

While the dehydration of formic acid (FA) to produce high-purity carbon monoxide (CO) is theoretically promising, practical application has been hindered by the lack of cost-effective catalysts with high selectivity and stability. In this study, using a straightforward method, we synthesize tungsten carbide (WC) nanoparticles uniformly distributed on porous foam carbon (WC@PFC). This catalyst can achieve a high CO production rate of 342.0 mmol g⁻¹h⁻¹ with 99.8 % selectivity at 250 °C, demonstrating its great potential for FA dehydration. In-situ diffuse reflectance infrared Fourier transform spectroscopy confirms the only reaction pathway for FA molecules to form CO and H₂O on WC@PFC through carboxyl (COOH*) intermediates. Density functional theory (DFT) calculations confirm that the COOH* intermediate is more likely to form CO/H₂O rather than CO₂/H₂, as the energy barrier for dehydration is lower than that for dehydrogenation. In addition, we utilize a custom-made TiC/Cu-based solar heating device to achieve a high temperature of 253 °C under a weak solar-irradiation intensity of 0.5 kW m⁻², which is enough for the thermal catalytic FA dehydration required. With the assistance of the solar heating device, the catalyst shows exceptional performance in photothermal catalytic experiments, maintaining CO selectivity near 100 %. The outstanding activity, high selectivity, and long-term stability of WC@PFC establish it as a promising catalyst for producing high-purity CO through FA dehydration under sunlight irradiation without external energy input.