Rapid Joule Heating Synthesis of Oxide-Socketed High-Entropy Alloy Nanoparticles as CO2 Conversion Catalysts

Abstract

The unorthodox surface chemistry of high-entropy alloynanoparticles(HEA-NPs), with numerous interelemental synergies, helps catalyzea variety of essential chemical processes, such as the conversionof CO2 to CO, as a sustainable path to environmental remediation.However, the risk of agglomeration and phase separation in HEA-NPsduring high-temperature operations are lasting issues that impedetheir practical viability. Herein, we present HEA-NP catalysts thatare tightly sunk in an oxide overlayer for promoting the catalyticconversion of CO2 with exceptional stability and performance.We demonstrated the controlled formation of conformal oxide overlayerson carbon nanofiber surfaces via a simple sol-gel method, whichfacilitated a large uptake of metal precursor ions and helped to decreasethe reaction temperature required for nanoparticle formation. Duringthe rapid thermal shock synthesis process, the oxide overlayer wouldalso impede nanoparticle growth, resulting in uniformly distributedsmall HEA-NPs (2.37 +/- 0.78 nm). Moreover, these HEA-NPs werefirmly socketed in the reducible oxide overlayer, enabling an ultrastablecatalytic performance involving >50% CO2 conversionwith>97% selectivity to CO for >300 h without extensive agglomeration.Altogether, we establish the rational design principles for the thermalshock synthesis of high-entropy alloy nanoparticles and offer a helpfulmechanistic perspective on how the oxide overlayer impacts the nanoparticlesynthesis behavior, providing a general platform for the designedsynthesis of ultrastable and high-performance catalysts that couldbe utilized for various industrially and environmentally relevantchemical processes.