Stabilized bismuth nanoplasmonics for selective CO₂ reduction to methanol at a heterointerface

Abstract

Photocatalytic CO2 transformation into value-added chemicals has enormous industrial importance, but is challenging to operate with multifaceted performances in activity, selectivity, stability and regenerability. We successfully achieved this goal by integrating plasmonic bismuth nanoparticles and non-plasmonic redox heterojunctions. This maximizes the product selectivity by directing the reaction paths via the electric field of localized surface plasmon resonances (LSPRs). We attach non-noble plasmonic Bi particles with a shell of BiOCl to self-assembled TiO2 nanosheets, creating a transformative hybrid plasmonic nanostructure for CO2-to-methanol conversion. It exhibits high photoactivity (235.26 µmol g-1 h-1), outstanding selectivity (∼90 % sole carbon/methanol product, ∼10 % H2) and is free of backward reactions, thanks to the synergistic effects of the hybrid nanostructure: complementary light absorption, strong local fields, and an adaptive redox heterojunction. Macro-to-micro experiments and simulations reveal that the BiOCl shell is responsible for stabilizing Bi to generate robust LSPRs, to induce 7–9 times local field enhancement, enabling efficient and selective CO2-to-methanol conversion at the TiO2-BiOCl heterointerfaces. This work demonstrates a durable and easily-regenerable photocatalyst with the capability to tune the CO2 reduction pathway by plasmon fields. Moreover, it provides a unique paradigm to harvest hydrogen carriers (liquid methanol and hydrogen gas) from the greenhouse gas CO2.