Tin sulfide supported on cellulose nanocrystals-derived carbon as a green and effective catalyst for CO2 electroreduction to formate

This work reports a whole green two-step approach for the synthesis of novel catalysts for efficient CO2 conversion. A conductive carbon support was firstly obtained via pyrolysis of cellulose nanocrystals (CNCs), and the carbon surface was successively decorated with tin sulfide (SnS) through a microwave-assisted hydrothermal process. The morphology and carbon structure were characterized by field emission scanning electron microscopy and Raman spectroscopy, and the presence of SnS decoration was confirmed by X-ray photoelectron spectroscopy and X-ray diffraction analyses. The SnS supported on CNC-derived carbon shows enhanced catalytic activity for the CO2 conversion to formate (HCOO-). Good selectivity of 86% and high partial current density of 55 mA cm(-2) are reached at - 1.0 V vs. reversible hydrogen electrode in KHCO3 electrolyte. Additionally, the mass activity of the composite catalyst achieves a value as high as 262.9 mA mgSn(-1) for HCOO- formation, demonstrating good utilization efficiency of Sn metal. In this work, the low-cost CNC-derived carbon is evidenced to be easily decorated with metal species and thus shows high versatility and tailorability. Incorporating metal species with conductive high-surface carbon supports represents an effective strategy to realize active and stable electrocatalysts, allowing efficient utilization of metals especially the raw and precious ones.