Copper doping enables safer, cost-effective hydrogen peroxide production

Hydrogen peroxide, the common household antiseptic used to clean cuts and scrapes, can also power space shuttles. While the version sold in pharmacies is far less concentrated than what is used in industry, the mere reduction of two hydrogen and two oxygen atoms into water and an extra oxygen can produce big results. The compound’s production is costly, though, requiring expensive metals to trigger the necessary chemical reactions that, when left unchecked, can produce unintentional explosions.

 

To produce safer, more economic and environmental hydrogen peroxide, an international research team turned to copper. The common metal helped reduce the number of manufacturing steps, making the resulting hydrogen peroxide more stable, efficient and cost-effective. They published their work on Jan. 11 in Nano Research.

 

Hydrogen peroxide is considered a high-value oxidant — a substance that can accept electrons from other substances, according to paper author Qian Liu, associate professor at Chengdu University’s Institute for Advanced Study. It is traditionally produced through a multi-step process in which an expensive metal, such as palladium, electrochemically reacts with a chemical compound containing hydrogen and oxygen to reduce the oxygen’s electrons by four to produce hydrogen peroxide and unwanted organic waste.

 

“The four-electron reduction process generates hydrogen peroxide and water — there is competition between the two processes,” Liu said. “As such, in the process of designing and preparing catalysts, we need to satisfy a two-electron reaction process to selectively produce hydrogen peroxide as much as possible to reduce unnecessary energy loss.”

 

The researchers opted to use titanium dioxide as an abundant, non-toxic and stable catalyst, but need to enhance it to achieve a two-electron reaction process.

“We doped the titanium dioxide with copper to naturally increase oxygen vacancy concentration, leading to improved electronic conductivity and better generation of hydrogen peroxide,” said paper author Shihai Yan, associate professor, College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University.

 

Copper serves as a heteroatom, which allows the researchers to manipulate the electronic structure of titanium dioxide. This enhanced catalyst can then create new atomic vacancies in the reduction compounds, encouraging one product over another. For example, when electrochemically reducing molecular hydrogen and oxygen, the addition of copper helps create more spots for oxygen to bond with hydrogen to produce hydrogen peroxide. Instead of a competition for the constituents to become water or hydrogen peroxide, the latter gets a boost, while the rest burns off as gas. When the process is contained in liquid, that’s a relatively harmless side effect.

 

“Two-electron electroreduction of oxygen into hydrogen peroxide in an aqueous environment provides a safe, sustainable and energy-saving method for on-demand production,” said Xuping Sun, professor, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China

 

“Copper-doped titanium dioxide exhibits a significantly improved selectivity of up to 91.2% for hydrogen peroxide, meaning that most of components reduce into the desired product. Moreover, it also shows a larger yield and good stability.”

 

Next, the researchers plan to design and synthesize copper-doped titanium dioxide catalysts against practical requirements to achieve large-scale industrial production.

 

“This study provides a new route to adjust the electronic structure of metal oxide by heteroatom doping as high efficiency electrocatalysts for oxygen reduction reaction to produce hydrogen peroxide,” Liu said.  

Other contributors include co-first author Zhiqin Deng, co-first author Li Li, Yuchun Ren, Je Liang, Kai Dong and Tingshuai Li, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China; Chaoqun Ma, College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University; Yonglan Luo, Institute for Advanced Study, Chengdu University; Bo Tang, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University; Yang Liu and Shuyan Gao, School of Materials Science and Engineering, Henan Normal University; and Abdullah M. Asin, Chemistry Department, Faculty of Science & Center of Excellence for Advanced Materials Research, King Abdulaziz University.

 

The National Natural Science Foundation of China supported this work.

 

 

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About Nano Research 

 

Nano Research is a peer-reviewed, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society. It offers readers an attractive mix of authoritative and comprehensive reviews and original cutting-edge research papers. After more than 10 years of development, it has become one of the most influential academic journals in the nano field. Rapid review to ensure quick publication is a key feature of Nano Research. In 2020 InCites Journal Citation Reports, Nano Research has an Impact Factor of 8.897 (8.696, 5 years), the total cites reached 23150, and the number of highly cited papers reached 129, ranked among the top 2.5% of over 9000 academic journals, ranking first in China's international academic journals.

 

About Tsinghua University Press

 

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