Decarbonizing the chemical industry and achieving carbon-neutral energy is paramount to the sustainability of the human species on earth. Electrocatalysis using transition metalbased catalysts plays a major role in achieving this task. In this work, we present an overview on the application of transition metal-based catalysts in electrocatalytic reactions. We particularly focus on the advancement of the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), nitrogen reduction reaction (NRR), and carbon dioxide reduction reaction (CO 2 RR) using transition metal electrocatalysts. We also aim to highlight the major achievements in these fields and the limitations in their large-scale industrial applications. Different transition metal catalysts are discussed, from 3-dimensional to 1-to 0-dimensional structures. We place special attention to the emerging transition metal catalysts such as 2dimensional carbide and nitride MXenes and single atom catalysts. Lastly, we offer recommendation for future research directions for the aforementioned electrocatalysis fields using transition metal electrocatalysts. This work will ultimately help both existing and incoming researchers in these fields in providing the state-of-the-art research findings and identifying the major challenges that must be addressed in order to attain carbon-neutral energy.

Reducing the concentration of CO2 from the atmosphere has attracted a lot of attention given the rapid level of industrialization in the world. Process Industries are one of the major contributors to this pollution in terms of the incessant release of CO2 from flue gas streams. In recent times metal oxides have received a lot of attention as potential adsorbents for solving this problem.They find application in post-, pre-, and oxy-combustion conditions. Their basic sites plus a lower charge to radius ratio increase their ionic nature and site basicity and facilitate the capture of this pernicious gas from flue gas streams by reacting to form carbonates, which when heated liberates an almost pure stream of CO2 which can be sequestered, thereby, aiding the release of environmentally benign flue gas streams to the atmosphere. This work takes a concise review of these metal oxides that have been widely studied.