Colloidal silver diphosphide (AgP<sub>2</sub>) nanocrystals as low overpotential catalysts for CO<sub>2</sub> reduction to tunable syngas.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31844056.
- Also identified by DOI 10.1038/s41467-019-13388-8 and PMC identifier 6915715.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Production of syngas with tunable CO/H<sub>2</sub> ratio from renewable resources is an ideal way to provide a carbon-neutral feedstock for liquid fuel production. Ag is a benchmark electrocatalysts for CO<sub>2</sub>-to-CO conversion but high overpotential limits the efficiency. We synthesize AgP<sub>2</sub> nanocrystals (NCs) with a greater than 3-fold reduction in overpotential for electrochemical CO<sub>2</sub>-to-CO reduction compared to Ag and greatly enhanced stability. Density functional theory calculations reveal a significant energy barrier decrease in the formate intermediate formation step. In situ X-ray absorption spectroscopy (XAS) shows that a maximum Faradaic efficiency is achieved at an average silver valence state of +1.08 in AgP<sub>2</sub> NCs. A photocathode consisting of a n<sup>+</sup>p-Si wafer coated with ultrathin Al<sub>2</sub>O<sub>3</sub> and AgP<sub>2</sub> NCs achieves an onset potential of 0.2 V vs. RHE for CO production and a partial photocurrent density for CO at -0.11 V vs. RHE (j<sub>-0.11, CO</sub>) of -3.2 mA cm<sup>-2</sup>.