New catalyst that makes production of industrial chemicals greener and simpler

Researchers have developed a simple, sustainable and economic way to make the common household and industrial chemical, hydrogen peroxide.

The novel way also opens potential pathways to the production of other chemicals and decentralisation of their production.

CSI Research Fellow, Yan Li uses electrochemical oxygen reduction reaction (ORR) tests to evaluate the performance of their novel catalyst (Image credit: Dr Shuangyue Wang, UNSW)

Hydrogen peroxide, as a bleach, dye, and disinfectant, is crucial to a range of industries such as pulp and paper, food and beverages, water treatment, textiles and laundry, healthcare, mineral and metal processing, and semi-conductor manufacture. It has a global market value of about US$4 billion and its demand continues to rise.

Nearly all hydrogen peroxide production today, however, relies on the chemical-based Anthraquinone process developed in the 1940s that is complex and energy intensive, requiring high temperatures and pressures. The process also uses organic solvents and generates wastewater and byproducts that contribute to carbon emissions.

Researchers at the Australian Research Council (ARC) Centre of Excellence for Carbon Science and Innovation (COE-CSI) have developed a novel catalyst that uses just water and oxygen to rapidly generate hydrogen peroxide at ambient temperature and pressure.

Equally novel is the dual role of this catalyst. Alongside producing the intermediate OOH groups for hydrogen peroxide production, it can rapidly generate protons from the hydrolysis of water – a rate determining step that is normally slow and severely limits efficient production of hydrogen peroxide.

“Most research has only focused on one part of the reaction, the oxygen reduction part, to either get water or hydrogen peroxide,” says Dr Yan Li, opens in a new window, the first author of the paper.

“Researchers have not examined it together with the proton feeding (proton-coupled electron transfer) to produce hydrogen peroxide. This is a mechanism that can also be applied to the synthesis of other valuable chemicals such as the conversion of nitrate waste to ammonia, an equally important industrial chemical crucial in the production of fertilisers, refrigerants and for water purification,” she says.

One catalyst, multiple benefits

A catalyst is something that speeds up a reaction without itself getting consumed or altered in the reaction. The construction and components of COE-CSI’s novel catalyst makes it fast, efficient and highly specific at producing only hydrogen peroxide.

This catalyst is part of a simple flow electrocatalytic system that feeds in water and oxygen at one end and, via the specific catalytic reactions that occur at ambient conditions, will generate hydrogen peroxide, with no unwanted byproducts.

Further, the system’s simplicity, safety, and low operational cost make it feasible for decentralised hydrogen peroxide production.

Unlike conventional large-scale, energy-intensive industrial processes, this approach allows for flexible, on-site chemical generation.

“For instance, a hospital could implement a system tailored to its needs, operating on demand or continuously. The setup is modular. If more hydrogen peroxide is required, additional or larger electrochemical flow cells can be incorporated,” says Centre Associate Investigator, Prof Yang Hou, from Zhejiang University.

“It is scalable depending on need and it can be done anywhere, eliminating the need for long-distance transport of chemicals from centralised production facilities to the end user,” says Prof Hou.

Innovative catalytic design

The dual role of COE-CSI’s catalyst emerges from its hybrid composition that includes the metals nickel, tellurium, and palladium. The nickel and tellurium, in the molecular form of NiTe₂, facilitate the reduction of oxygen – the process of molecular oxygen gaining electrons.  The palladium is in the form of nano-sized clusters – just 4-5 atoms per cluster – that are attached to the NiTe₂ (NiTe₂-Pd). Its role is to catalyse the dissociation of water into protons and hydroxyl species (OH-). The resulting intermediate OOH groups and free protons are then able to combine to make hydrogen peroxide (H₂O₂).

Two critical metrics, selectivity and the Faradaic Efficiency, are used to evaluate a catalyst’s performance.

NiTe₂-Pd achieves a selectivity of 99% which means it almost exclusively directs the oxygen and water molecules to form hydrogen peroxide. That is, it suppresses or avoids almost all unwanted side reactions from happening.

NiTe₂-Pd’s Faradaic Efficiency is an equally impressive 95%, which essentially means that nearly all electrons flowing through the system contribute directly to generating hydrogen peroxide. This is one of the highest reported efficiencies for hydrogen peroxide catalytic systems.

Further, the catalyst’s proton-coupled electron transfer capability is highly applicable for other catalytic processes such as the electroreduction of nitrate waste to ammonia.

The future is carbon

COE-CSI’s multi-disciplinary research teams are committed to pioneering advanced carbon materials and technologies for renewable energy generation and clean chemical production to help achieve net-zero carbon emissions.

“Although this catalyst is metal-based, COE-CSI will integrate a highly porous 3D carbon support to enhance its performance,” says Centre Director, Professor Liming Dai, opens in a new window.

“The 3D carbon support offers multiple advantages. It provides a massive surface area to house active catalytic sites, it facilitates efficient electrolyte transport via the highly porous structure, and the carbon itself enhances rapid electron conductivity.

These properties will significantly boost the catalytic reaction kinetics (the speed at which things happen), further accelerating hydrogen peroxide production,” says Prof Dai.

While this catalyst is scalable and commercially viable, CSI’s ultimate objective is to replace expensive, unsustainable noble metal catalysts like palladium with low-cost and earth-abundant carbon-based alternatives.

About CSI

The ARC Centre of Excellence for Carbon Science and Innovation (COE-CSI), opens in a new window is a research centre that brings together a multidisciplinary team of world leading experts from Australia and abroad to revolutionise carbon science and technology for clean production of energy and chemicals. This work is supported partially by the National Natural Science Foundation of China and the Australian Research Council.

Enquiries and more information

Jason Major (Communications and Outreach Officer)
Email: comms.csi@unsw.edu.au, opens in a new window
(Feature image credit: Dr Yan Li, UNSW)

Tags: carbon, opens in a new window, catalyst, opens in a new window, green chemistry, opens in a new window, Yan Li, opens in a new window