High entropy nanoalloys for electrocatalytic plastic waste upcycling

Plastic pollution has become a global issue due to improper management of plastic waste, posing a significant environmental burden. Microplastic pollution is also widely recognized as a health hazard, and there is an urgent need to develop methods to upcycle plastic waste into value-added chemicals and precursors. Among upcycling approaches, electrocatalytic upcycling is gaining attention as a key technology for converting waste plastics, such as polyethylene terephthalate, polyethylene, and polystyrene, into value-added chemicals and fuels. High-entropy alloy (HEA) nanostructures are an emerging class of nanomaterials with five or more elements in near-equimolar ratios, which support catalytic oxidation of complex reactions involving plastic hydrolysate. In this review, we first focused on high-entropy alloy nanostructures that have been employed as electrocatalysts for the oxidation of plastic hydrolysate derived from various plastic wastes. We have specifically highlighted the product selectivity and conversion efficiency attained due to the availability of multi-metal HEA nanostructures. The influence of HEA dimensionality, size, and multi-site synergism on the electrocatalysis of plastic waste hydrolysates, including ethylene glycol, lactic acid, and glycolic acid, is discussed in detail. The stability aspects of HEA nanostructures, along with their performance in lab-scale test setups such as H-Cell and flow cell, are summarized. This review also outlines the challenges that need to be addressed to further develop active, stable HEAs and presents the future prospects of the electrocatalytic upcycling process for wide-scale adoption.