A powerful catalyst for electrolysis of water that could help exploit renewable energies

The importance of researching and improving renewable sources of energy is becoming increasingly important. One of the strategies for generating energy is to separate the water molecules (H2O) in an electrochemical reaction called electrolysis. This process allows us to convert the energy of the sun or other renewable sources into chemical energy. However, the electrochemical fractionation of water molecules requires an overpotential – an excess of voltage to be applied in addition to the theoretical voltage (1.23 V compared to a reversible hydrogen electrode or RHE) so that the necessary reactions can occur.

Electrocatalysts are materials that, because of their electrical and morphological characteristics, facilitate electrochemical processes. The researchers looked for electrocatalysts that can contribute to the electrolysis of water. Some of the best catalysts are noble, rare and expensive metal oxides. Fortunately, compounds based on nickel hydroxide (Ni (OH) 2) are a better alternative.

A team of scientists, including teachers. Hyunsik Im and Hyungsang Kim of Dongguk University have interposed poly (OH) 2 nanoparticles of polyoxovanadate (POV) arranged in ordered layers. They used a promising method called "chemical solution growth" (CSG), in which a highly saturated solution is prepared and the desired material structure naturally forms when solutes precipitate in a predictable and controlled manner, creating a layer-by-layer structure with POV nanoclusters interposed between the Ni (OH) 2 layers.

The team demonstrated that the resulting card house structure significantly reduced the excessive potential for electrolysis of water. They attributed this to the morphological characteristics of this material; POV nanoclusters increase the spacing between Ni (OH) 2 layers and induce the formation of micropores, increasing the surface of the final material and the number of catalytic sites where water molecules can be fractionated . "Our results demonstrate the benefits of the CSG method for optimizing the pore structure of the material obtained," says Professor Im.

Facilitating the electrolysis of water with the help of new catalysts is a step towards a greener future. In addition, the CSG method could be useful in many other areas. "The CSG's easy deposit of nanohybrid materials can be useful for applications such as the production of Li-ion batteries and biosensors," says Professor Kim. Only time will tell us what new uses the CSG will find.

###

Authors: Jayavant L. Gunjakar1,2, Bo Hou3, Akbar I. Inamdar1, Sambhaji M. Pawar1,

Abu Talha Aqueel Ahmed1, Harish S. Chavan1, Jongmin Kim1, Sangeun Cho1,

Seongwoo Lee1, Yongcheol Jo1, Seong-Ju Hwang4, Tae Geun Kim5, SeungNam Cha3,

Hyungsang Kim1 * and Hyunsik Im1 *

Title of the original article: Nanoporous Nanohybrids Hydroxydated and Layered Coupled with Zero-Dimensional Polyoxovanadate Nanoclusters for Enhanced Oxidation Catalysis of Water

Newspaper: Small

DOI: 10.1002 / smll.201703481

Affiliations: 1Division of Physics and Semiconductor Sciences, Dongguk University

2D. Y. Patil Education Company

3Department of Engineering Science, University of Oxford

4Center for Nano-Bio-Intelligent Materials (CINBM), Department of Chemistry and Nanosciences, Ewha Womans University

5Ecole of Electrical Engineering, University of Korea

* Email from the corresponding author: H. Kim ([email protected]); H. Im ([email protected])