Polar Bear Hair Inspired Supra-Photothermal Promoted Water Splitting

The photothermal effect has recently been applied to oxygen evolution reaction (OER) electrodes, which can effectively convert solar energy into heat to promote the reaction kinetics. However, optimized materials that can more efficiently collect and utilize solar energy are demanded. Here, inspired by the thermal insulation ability of polar bear hairs, we fabricated a villous carbon frameworks (VCF) embedded with FeNi3 alloys. Under illumination, the achieved local temperature surpassed the bare carbon frameworks (CF). This highly promoted the OER performance of the inner electrocatalysts. With light illumination intensity of 0.25 W cm–2, the VCF demonstrated an overpotential of 194 mV to deliver 100 mA cm–2 current density. The current density at 1.45 V could reach over 300 mA cm–2, about 8.5-fold of that without illumination, outperforming traditional photothermal electrocatalysts. Meanwhile, quasi-operando soft X-ray absorption spectroscopy (SXAS) manifested that the photothermal effect of the VCF would boost the electron rearrangement of iron–nickel species during OER and optimize the adsorption of oxygen intermediates. Our design principle was transferable to other catalysts whose performance could be accelerated by the photothermal effect.