Photoelectrocatalytic Transformations of Waste into Value

Waste-to-energy technologies based on renewable energy promote the resource circular economy by upcycling resources while reducing carbon emissions. Photoelectrocatalytic (PEC) systems emerge as a promising platform by harnessing solar energy to convert diverse waste streams, such as biomass, plastics, and nitrate-containing effluents, into high-value chemicals and renewable fuels. This review provides a comprehensive overview of PEC-enabled waste valorization. We cover the fundamental mechanism of photoelectrocatalysis, the types of waste-derived feedstocks as reaction substrates, and the economic potential of conversion products. Specifically, biomass oxidation, plastic oxidation, and nitrate reduction are examined as representative examples of PEC applications. The structural features and performance of photoelectrodes used for selective conversion to target products are systematically discussed. PEC techniques and advanced analytical tools applied to elucidate reaction mechanisms are also highlighted, offering critical insights into the interplay between material design and catalytic activity. Next, we discuss tandem structures that combine these waste valorization reactions. This review aims to provide systematic information and future research directions on the study of PEC waste-to-value conversion.