Recent Advances in Carbon Dioxide Adsorption, Activation and Hydrogenation to Methanol using Transition Metal Carbides

The inevitable emission of carbon dioxide (CO₂ ) due to the burning of a substantial amount of fossil fuels has led to serious energy and environmental challenges. Metal-based catalytic CO₂ transformations into commodity chemicals are a favorable approach in the CO₂ mitigation strategy. Among these transformations, selective hydrogenation of CO₂ to methanol is the most promising process that not only fulfils the energy demands but also re-balances the carbon cycle. The investigation of CO₂ adsorption on the surface of heterogeneous catalyst is highly important because the formation of various intermediates which determines the selectivity of product. Transition metal carbides (TMCs) have received considerable attention in recent years because of their noble metal-like reactivity, ceramic-like properties, high chemical and thermal stability. These features make them excellent catalytic materials for a variety of transformations such as CO₂ adsorption and its conversion into value-added chemicals. Herein, the catalytic properties of TMCs are summarize along with synthetic methods, CO₂ binding modes, mechanistic studies, effects of dopant on CO₂ adsorption, and carbon/metal ratio in the CO₂ hydrogenation reaction to methanol using computational as well as experimental studies. Additionally, this Review provides an outline of the challenges and opportunities for the development of potential TMCs in CO₂ hydrogenation reactions.

3D Co-Ni-C Network from Milk as Competitive Bifunctional Catalysts for Methanol and Urea Electrochemical Oxidation

Methanol oxidation (MOR) and urea oxidation (UOR) have been considered for new types of fuel cells, but the lack of highly active nonnoble metal catalysts restricts such cells. A NiCo-modified biomass carbon (milk as the carbon source)-based catalyst with a 3D structure is synthesized by using salt templates. The results show that 3D-C-NiCo (1:1) exhibits excellent MOR and UOR properties with a potential of 1.33 V vs. RHE and 1.35 V vs. RHE at 10 mA cm−2, respectively. MOR and UOR reactions not only can replace the oxygen evolution reaction (OER) in consumption of electrolytic water but also can effectively degrade wastewater pollution rich in methanol and urea.