Noble-Metal-Free High-Entropy Alloy Nanoparticles for Efficient Solar-Driven Photocatalytic CO2 Reduction.

Metal nanoparticle cocatalysts are widely investigated for their ability to enhance the performance of photocatalytic materials, however their practical application is often limited by the inherent instability under light irradiation. This challenge has catalyzed interest in exploring high-entropy alloys (HEAs), which, with their increased entropy and lower Gibbs free energy, provide superior stability. In this study, we successfully synthesized 3.5 nm sized noble-metal-free nanoparticles (NPs) composed of a FeCoNiCuMn HEA. With theoretic calculation and experiments, the electronic structure of HEA in augmenting the catalytic CO2 reduction has been uncovered, including the individual roles of each element and the collective synergistic effects. We then investigated their photocatalytic CO2 reduction capabilities when immobilized on TiO2. HEA NPs significantly enhanced the CO2 photoreduction, achieving a 23-fold increase over pristine TiO2, with CO and CH4 production rates of 235.2 µ mol g-1 h-1 and 19.9 µ mol g-1 h-1, respectively. Meanwhile, HEA NPs showed excellent stability under simulated solar irradiation, as well high-energy X-ray irradiation. This research emphasizes the promising role of HEA nanoparticles, composed of earth-abundant elements, in revolutionizing the field of photocatalysis. This article is protected by copyright. All rights reserved.