A Sustainable Synthesis of Nickel-Nitrogen-Carbon Catalysts for Efficient Electrochemical CO2 Reduction to CO

Abstract

The electrochemical CO2 reduction reaction (CO2RR) is a promising approach of using renewable power sources such as wind and solar to convert CO2 into value-added products. However, conventional methods of synthesizing high-performance CO2RR catalysts usually produce wastes and are not environmentally friendly. Herein, we developed a sustainable catalyst synthesis method by using cheap, abundant cornstarch as the feedstock, and doping it with nickel (Ni) from a simulated metalcontaining wastewater, before finally doping it with nitrogen (N) to create a highly efficient metal-nitrogen-carbon (M-N-C) catalyst that is dominated by single atomic Ni sites without the need for an acid wash post-treatment. The cornstarch-based catalyst demonstrated a high faradaic efficiency (FE) of 92% for CO production with a CO current density of 11.6 mA/cm 2 at −0.8 V versus reversible hydrogen electrode (RHE). At the same Ni content under the same testing conditions, a catalyst prepared via conventional wet impregnation only attained a CO current density of 9.3 mA/cm 2 , and a catalyst prepared using more expensive graphene oxide achieved a CO current density of 11.5 mA/cm 2 but with a lower FE (CO) at 81%. Findings from this work provide insights into using low-cost sustainable biomaterials and non-waste producing methods to produce effective electrochemical CO2RR catalysts.

Energy conversion efficiency comparison of different aqueous and semi-aqueous CO2 electroreduction systems

“…To calculate the energy conversion efficiency for CO 2 electroreduction, we examined the literature using the CAS SciFinder software and calculated the efficiencies in 107 typical aqueous and semi-aqueous systems. 13–73 We selected the literature reports with a relatively high frequency of citations over the last 30 years. The pH of each CO 2 -saturated solution required for the calculation in this work was measured using an F-53 pH meter (HORIBA, Ltd).…”

Preparation of Au-RGO/TiO2 nanotubes and study on the photocatalytic degradation of ciprofloxacin

“…In this study, Au-RGO/TiO 2 composite material was prepared by electrochemical deposition method 38,39 to improve the shortcomings of low visible light utilization efficiency and the fast photoelectron–hole recombination of TiO 2 . The photocatalytic properties of the composite were tested with ciprofloxacin as the target pollutant, and the modification mechanism, photocatalytic reaction mechanism, and degradation pathway of ciprofloxacin are discussed in detail.…”

“…Due to the high efficiency and low cost of composite nanomaterials, most researchers have focused on the photocatalytic technology of using composite nanomaterials to treat wastewater and degrade pollutants in water. [35][36][37] In this study, Au-RGO/TiO 2 composite material was prepared by electrochemical deposition method 38,39 to improve the shortcomings of low visible light utilization efficiency and the fast photoelectron-hole recombination of TiO 2 . The photocatalytic properties of the composite were tested with cipro-oxacin as the target pollutant, and the modication mechanism, photocatalytic reaction mechanism, and degradation pathway of ciprooxacin are discussed in detail.…”

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

“…Recently, metal-free nanocarbons such as carbon nanotubes, graphene, carbon black, etc., and their composites have been widely used in the fields of catalysis, electrochemistry, and environmental remediation. − In this regard, the use of nonmetallic nanocarbons as the catalyst in this reaction has also attracted extensive attention. Because of the excellent physical/chemical properties and easy-to-control surface electronic properties, nanocarbons are widely used as the catalysts for the oxidative activation of methane, , dehydrogenation (ODH) of hydrocarbons, , hydrogenation of nitrobenzene, hydroxylation of benzene, selective oxidations, , and so on.…”