Ar ational design for oxygen evolution reaction (OER) catalysts is pivotal to the overall efficiency of water electrolysis.M uchw ork has been devoted to understanding cation leaching and surface reconstruction of very active electrocatalysts,b ut little on intentionally promoting the surface in acontrolled fashion. We now report controllable anodic leaching of Cr in CoCr 2 O 4 by activating the pristine material at high potential, which enables the transformation of inactive spinel CoCr 2 O 4 into ah ighly active catalyst. The depletion of Cr and consumption of lattice oxygen facilitate surface defects and oxygen vacancies,exposing Co species to reconstruct into active Co oxyhydroxides differ from CoOOH. An ovel mechanism with the evolution of tetrahedrally coordinated surface cation into octahedral configuration via non-concerted proton-electron transfer is proposed. This work shows the importance of controlled anodic potential in modifying the surface chemistry of electrocatalysts.

A rational design for oxygen evolution reaction (OER) catalysts is pivotal to the overall efficiency of water electrolysis. Much work has been devoted to understanding cation leaching and surface reconstruction of very active electrocatalysts, but little on intentionally promoting the surface in a controlled fashion. We now report controllable anodic leaching of Cr in CoCr2O4 by activating the pristine material at high potential, which enables the transformation of inactive spinel CoCr2O4 into a highly active catalyst. The depletion of Cr and consumption of lattice oxygen facilitate surface defects and oxygen vacancies, exposing Co species to reconstruct into active Co oxyhydroxides differ from CoOOH. A novel mechanism with the evolution of tetrahedrally coordinated surface cation into octahedral configuration via non‐concerted proton‐electron transfer is proposed. This work shows the importance of controlled anodic potential in modifying the surface chemistry of electrocatalysts.

No abstract

No abstract

Global demand for energy consumption has been on the rise over the years with globalization and population growth. However, the current usage of fossil fuel as our main energy source raised concerns over the impact on our environment. Hydrogen appears to be the ideal replacement with scalable water electrolysis from renewable energy sources. However, the sluggish kinetics of oxygen evolution reaction (OER) cause it to be expansive and hindered its usage. Therefore it is important to develop an efficient OER catalyst based on first row transition metals to make water oxidation economical. For many years, different transition metal based oxides OER catalyst like perovskite, spinels, layered hydroxides and amorphous oxides/hydroxides have been explored. Recently, surface amorphisation and reconstruction of the catalyst during electrochemical cycling through OER was discovered to boost the OER performance. To engineer and advance our understanding on in-situ surface reconstruction, Cr leaching phenomenon from CoCr2O4 was investigated. Various characterization techniques like CV, CA, ICP, XPS, XAS and TEM techniques were employed to study the active species of OER. The leaching 1.3 Objective and Scope "The present research is concerned with the leaching of Cr from CoCr2O4 to expedite surface reconstruction and in turn enhance its OER performance and provide deeper understanding for application as an OER electrocatalyst.