Revocatus L. Machunda

Bio: Revocatus L. Machunda is an academic researcher from African Institute of Science and Technology. The author has contributed to research in topics: Adsorption & Fluoride. The author has an hindex of 13, co-authored 61 publications receiving 637 citations. Previous affiliations of Revocatus L. Machunda include Nelson Mandela African Institute of Science and Technology & Gwangju Institute of Science and Technology.

Sustainable production of formic acid by electrolytic reduction of gaseous carbon dioxide

Abstract: A tin (Sn) nanostructure has been applied to a gas diffusion electrode for the direct electro-reduction of carbon dioxide (CO2) in a zero-gap electrolytic cell. A Sn catalyst layer was evenly applied to a carbon substrate by a controlled spraying technique and the efficient catalytic conversion of gas-phase CO2 to formic acid (HCOOH) demonstrated. We observed that the overall mean faradaic efficiency towards HCOOH remained above 5.0% over the entire reduction time. In addition, due to its compact configuration and surroundings at near ambient conditions the approach described is promising in both modularity and scalability. Sustainable energy sources such as solar, wind, or geothermal electricity could be used as a power source to minimize the large-scale operating cost.

Electrocatalytic Recycling of CO2 and Small Organic Molecules

Abstract: As global warming directly affects the ecosystems and humankind in the 21st century, attention and efforts are continuously being made to reduce the emission of greenhouse gases, especially carbon dioxide (CO2). In addition, there have been numerous efforts to electrochemically convert CO2 gas to small organic molecules (SOMs) and vice versa. Herein, we highlight recent advances made in the electrocatalytic recycling of CO2 and SOMs including (i) the overall trend of research activities made in this area, (ii) the relations between reduction conditions and products in the aqueous phase, (iii) the challenges in the use of gas diffusion electrodes for the continuous gas phase CO2 reduction, as well as (iv) the development of state of the art hybrid techniques for industrial applications. Perspectives geared to fully exploit the potential of zero-gap cells for CO2 reduction in the gaseous phase and the high applicability on a large scale are also presented. We envision that the hybrid system for CO2 reduction supported by sustainable solar, wind, and geothermal energies and waste heat will provide a long term reduction of greenhouse gas emissions and will allow for continued use of the abundant fossil fuels by industries and/or power plants but with zero emissions.

A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels

Abstract: This paper reviews recent progress made in identifying electrocatalysts for carbon dioxide (CO2) reduction to produce low-carbon fuels, including CO, HCOOH/HCOO−, CH2O, CH4, H2C2O4/HC2O4−, C2H4, CH3OH, CH3CH2OH and others. The electrocatalysts are classified into several categories, including metals, metal alloys, metal oxides, metal complexes, polymers/clusters, enzymes and organic molecules. The catalyts' activity, product selectivity, Faradaic efficiency, catalytic stability and reduction mechanisms during CO2 electroreduction have received detailed treatment. In particular, we review the effects of electrode potential, solution–electrolyte type and composition, temperature, pressure, and other conditions on these catalyst properties. The challenges in achieving highly active and stable CO2 reduction electrocatalysts are analyzed, and several research directions for practical applications are proposed, with the aim of mitigating performance degradation, overcoming additional challenges, and facilitating research and development in this area.

Recent Advances in Inorganic Heterogeneous Electrocatalysts for Reduction of Carbon Dioxide

Abstract: In view of the climate changes caused by the continuously rising levels of atmospheric CO2 , advanced technologies associated with CO2 conversion are highly desirable. In recent decades, electrochemical reduction of CO2 has been extensively studied since it can reduce CO2 to value-added chemicals and fuels. Considering the sluggish reaction kinetics of the CO2 molecule, efficient and robust electrocatalysts are required to promote this conversion reaction. Here, recent progress and opportunities in inorganic heterogeneous electrocatalysts for CO2 reduction are discussed, from the viewpoint of both experimental and computational aspects. Based on elemental composition, the inorganic catalysts presented here are classified into four groups: metals, transition-metal oxides, transition-metal chalcogenides, and carbon-based materials. However, despite encouraging accomplishments made in this area, substantial advances in CO2 electrolysis are still needed to meet the criteria for practical applications. Therefore, in the last part, several promising strategies, including surface engineering, chemical modification, nanostructured catalysts, and composite materials, are proposed to facilitate the future development of CO2 electroreduction.

Nanostructured Tin Catalysts for Selective Electrochemical Reduction of Carbon Dioxide to Formate

Abstract: High surface area tin oxide nanocrystals prepared by a facile hydrothermal method are evaluated as electrocatalysts toward CO2 reduction to formate. At these novel nanostructured tin catalysts, CO2 reduction occurs selectively to formate at overpotentials as low as ∼340 mV. In aqueous NaHCO3 solutions, maximum Faradaic efficiencies for formate production of >93% have been reached with high stability and current densities of >10 mA/cm(2) on graphene supports. The notable reactivity toward CO2 reduction achieved here may arise from a compromise between the strength of the interaction between CO2(•-) and the nanoscale tin surface and subsequent kinetic activation toward protonation and further reduction.