Concentrating and directing energy flow in plasmonic heterostructures for stable and efficient light-driven methane dry reforming

Methane dry reforming offers a promising approach for converting CH4 and CO2 into valuable syngas, while its application is restricted by catalyst deactivation and carbon deposition. Here, we report a well-designed heterostructured plasmonic photocatalyst consisting of a plasmonically active Ag core and a catalytically active Ir cage selectively grown on the vertices and edges of the Ag core, which preserves strong plasmonic absorption and enables the significant concentration of electromagnetic energy on the Ir cage, as well as the selective dissipation of that energy to generate hot carriers. This heterostructured plasmonic photocatalyst demonstrates long-term stability (300 h), high selectivity (>97%), and much enhanced H2 and CO production in light-driven methane dry reforming. We demonstrate that light-excited hot carriers, coupled with electron-enriched Ir sites, enhance the activation of CO2 and CH4, and facilitate the conversion of *CH intermediates to *CHO, thereby preventing coke formation and contributing to the high catalytic performance. Methane dry reforming is a promising way to convert greenhouse gases into syngas but suffers from catalyst deactivation and coking. Here, the authors design a plasmonic heterostructure that can concentrate and direct energy flow, enabling stable and efficient photocatalytic methane dry reforming.