Hetero-interfaces in the photo- and electrocatalytic separation of water

Water splitting has recently received a lot of attention as an environmentally friendly and economical method of producing hydrogen energy. Materials of diverse compositions, sizes, and interfaces are important for discovering suitable compounds for electrocatalysis and photocatalysis.

​​​​​​​Study: Nanoscale hetero-interfaces for electrocatalytic and photocatalytic separation of water. Image Credit: peterschreiber.media/Shutterstock.com

Hetero-interfaces have the potential not only to overcome the disadvantages of single-phase materials, but also to develop new capabilities for water separation applications.

An article accepted for publication in the journal Advanced Materials Science and Technology describes fundamental knowledge and experimental progress in the engineering of hetero-interfaces for the fabrication of materials for the separation of water by photocatalysis and electrocatalysis.

Hydrogen energy: why is it important?

The increasing use of fossil fuels has led to significant energy problems and environmental degradation. Sustainable and renewable energy is essential for maintaining clean and viable ecosystems in modern human society.

Molecular hydrogen is considered an excellent source of long-term energy. Due to its high energy density, hydrogen energy is expected to transform the global energy infrastructure in the future.

Hydrogen can be effectively used as a gaseous fuel to replace fossil fuels, and it can also be used to conserve additional energy by integrating fluctuating sustainable energy into the energy system.

Most hydrogen is currently produced by converting natural gas to steam. However, the usefulness of the process is limited due to the creation of dangerous pollutants like carbon dioxide. Although biomass is a regenerative hydrogen resource, it cannot meet the need for large-scale hydrogen production.

Consequently, efficient and environmentally acceptable hydrogen production techniques are urgently needed to meet global energy demand.

Fractionation of water for hydrogen generation

Water splitting is a fully renewable and efficient method of generating hydrogen energy, as hydrogen molecules can be formed by breaking water molecules using either sunlight or electrical energy .

The separation of water by photocatalysis and electrocatalysis offers the advantages of infinite water availability, large-scale production feasibility and high hydrogen production selectivity. Nevertheless, the hydrogen produced by photocatalysis and electrocatalysis contributes less than 5% of the overall hydrogen production.

Therefore, facilitating water separation for widespread industrialization is a difficult task. The separation of water can be divided into two different interactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). However, the separation of water by photocatalysis and electrocatalysis requires crossing a very energetic threshold due to the extremely stable nature of water.

Therefore, the development of catalysts with excellent reactivity, low energy expenditure and natural availability is essential for the large-scale implementation of water separation technology.

Nanoscale Heterostructures for Water Splitting Applications

Recently, the construction of hetero-interface electrocatalysts by integrating many active constituents has attracted significant attention for various water splitting technologies including photocatalysis and electrocatalysis.

Essentially, a heterojunction is a structure with an interlayer formed by stacking or stitching multiple components. The functionalities provided by the separate components result in the unique characteristics of heterostructured substances.

Heterostructures can significantly affect the intrinsic catalytic activity of separate components, resulting in unique physicochemical properties for specific procedures such as photocatalysis and electrocatalysis.

Highlights of the current study

In this article, researchers evaluated recent studies on the concept, properties, and advancement of hetero-interfaces in the electrocatalytic and photocatalytic separation of water. First, the fundamental concepts of water splitting by photocatalysis and electrocatalysis, as well as the main parameters influencing the catalytic activity, were discussed.

The researchers then described the essential properties of hetero-interfaces based on their morphology and electrical structure and highlighted the critical functions of heterojunctions in water splitting by electrocatalysis and photocatalysis.

According to the researchers, hetero-interfaces can offer band symmetry, space charge isolation, low deposition energy obstacles, greater catalytic activity and improved stability during the water separation process. .

Moreover, the water separation process can be effectively enhanced for the rapid generation of green hydrogen energy by strategically building the hetero-interfaces of the catalysts.

Future prospects

Despite significant advances in hetero-interfaces for electrocatalysis and photocatalysis, problems still need to be solved before the widespread industrialization of water separation technology.

For example, most available synthesis techniques make precise control of the hetero-interface configuration impossible. Accordingly, a universal and easy-to-control synthetic method for heterostructures is urgently required. Moreover, studying the catalytic reaction process at the interface is difficult due to the complexity of the junction and the unpredictability of the structure.

Accordingly, a well-defined interface and an in situ means of observing the catalytic activity of heterostructures must be developed to ensure the wide applicability of the water separation process.

Reference

Yang, B. et al. (2022). Nanoscale hetero-interfaces for electrocatalytic and photocatalytic separation of water. Advanced Materials Science and Technology. Available at: https://doi.org/10.1080/14686996.2022.2125827

Disclaimer: The views expressed herein are those of the author expressed privately and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork, the owner and operator of this website. This disclaimer forms part of the terms of use of this website.

Jack C. Nugent