Silicon Nanowire-Supported Catalysts for the Photocatalytic Reduction of Carbon Dioxide

The conversion of carbon dioxide, a greenhouse gas, into valuable chemicals using sunlight is highly significant technologically and holds the promise of providing a more sustainable alternative to fossil fuels. To effectively utilize the abundant solar irradiation, it is essential to develop catalysts that can absorb a significant portion of the solar spectrum, particularly in the UV, visible, and infrared regions. Silicon nanowire arrays grown on silicon substrates meet this criterion, as they can absorb over 85% of solar irradiation and show minimal reflective losses across the UV, visible, and infrared portions of the solar spectrum. Herein, we report the deposition of various catalysts, including iron oxyhydroxides, copper, nickel, and ruthenium, on silicon nanowires using different catalyst deposition techniques. The photocatalytic reduction of carbon dioxide was evaluated using these catalysts. The results show that silicon nanowires coated with nickel and ruthenium oxide had the highest activity towards the photocatalytic reduction of carbon dioxide, with photomethanation rates reaching 546 μmolgcat−1h−1 for RuO2@SiNWs and 278 μmolgcat−1h−1 for Ni/NiO@SiNWs. Continued improvement of photocatalysts using nanostructured silicon supports could enable the development of solar refineries for converting gas-phase CO2 into value-added chemicals and fuels.