Colloidal silver diphosphide (AgP2) nanocrystals as low overpotential catalysts for CO2 reduction to tunable syngas

Hui Li, Peng Wen, Dominique S. Itanze, Zachary D. Hood, Xiao Ma, Michael Kim, Shiba Adhikari, Chang Lu, Chaochao Dun, Miaofang Chi, Yejun Qiu, Scott M. Geyer

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83 Scopus citations

Abstract

Production of syngas with tunable CO/H2 ratio from renewable resources is an ideal way to provide a carbon-neutral feedstock for liquid fuel production. Ag is a benchmark electrocatalysts for CO2-to-CO conversion but high overpotential limits the efficiency. We synthesize AgP2 nanocrystals (NCs) with a greater than 3-fold reduction in overpotential for electrochemical CO2-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 AgP2 NCs. A photocathode consisting of a n+p-Si wafer coated with ultrathin Al2O3 and AgP2 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−0.11, CO) of −3.2 mA cm−2.

Original languageEnglish
Article number5724
JournalNature Communications
Volume10
Issue number1
DOIs
StatePublished - Dec 1 2019

Funding

This work was financially supported by Wake Forest University, and Shenzhen Bureau of Science, Technology and Innovation Commission (JCYJ 20160525163956782). A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This work benefited from the Shanghai Synchrotron Radiation Facility (SSRF).

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