Efficient photoelectrochemical synthesis of azo compounds via in situ surface reconstruction of BiVO4

" In this study, we systematically investigated the influence of electrolyte cations on the performance of BiVO₄ photoelectrodes during the oxidative coupling of aniline to azobenzene. Beyond performance metrics, we successfully uncovered the underlying mechanism responsible for this enhanced photoanode activity," said Dong Liu, corresponding author of this study and a specially appointed professor at the University of Science and Technology of China (USTC).

 

The team published their research article in Nano Research on June 5, 2026.

 

Azobenzene and its aromatic derivatives are widely used in dyes, photoresponsive materials, biomedicine, and smart display technologies. Their reversible cis-trans isomerization makes them highly valuable for applications such as optical data storage, photonic computing, and precision drug delivery. However, conventional synthetic methods for azo compounds often rely on precious-metal catalysts, hazardous reagents, and harsh reaction conditions. Photoelectrochemical (PEC) synthesis offers a promising, greener route for producing these compounds under mild conditions.

 

Among photoanode materials, BiVO₄ has attracted significant attention due to its favorable visible-light response and suitable band structure. However, its practical performance is often limited by sluggish charge transfer and severe carrier recombination. Therefore, improving charge-transfer efficiency and overall photoelectrochemical activity is essential for achieving efficient organic synthesis on BiVO₄-based photoelectrodes.

 

The research team improved the reaction performance of BiVO₄ by tuning the electrolyte composition during the photoelectrochemical oxidative coupling of aniline. Through detailed mechanistic studies, they discovered that the introduction of Cs⁺ induces the formation of a passivation layer on the BiVO₄ surface. This layer effectively suppresses the leaching of VO₄^3⁻ from the bulk lattice, stabilizes the electrode surface, and promotes the exposure of catalytically active Bi sites. Consequently, the reconstructed Cs-BiVO₄ photoanode exhibited a significantly enhanced interfacial charge-transfer capability while regulating the adsorption behavior of both substrates and products on the electrode surface. These combined effects were identified as the key origin of the improved azobenzene production.

 

Under 100 mW cm^-2 illumination and an applied bias of 1.8 V vs. RHE, the reconstructed Cs-BiVO₄ photoanode delivered a stable photocurrent density of 9.7 mA cm^-2 and an azobenzene production rate of 40 µmol cm^-2 h^-1, with a Faradaic efficiency exceeding 71%. This represents a substantial improvement over pristine BiVO₄. Additionally, this strategy demonstrated excellent generality, enabling the selective synthesis of a wide range of aromatic azo compounds.

 

“This work establishes a new pathway for developing efficient, sustainable photoelectrochemical systems for azo compound synthesis. Furthermore, it offers critical insights into surface regulation mechanisms, providing a blueprint for the rational design of high-performance photoelectrodes,” said Dong Liu.

 

The paper was authored by Ying-Ao Liu, Shenghe Si, Zehua Liu, and Dong Liu from University of Science and Technology of China.

 

This study was supported by the National Natural Science Foundation of China (22279128), the Fundamental Research Funds for the Central Universities (WK2140250024), and the Suzhou Key Laboratory of Bioinspired Interfacial Science (SZ2024004).

 

DOI Link:

https://doi.org/10.26599/NR.2026.94908568

 

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.

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