Breakthrough Imaging Technique Sheds Light on Nanoscale Photocatalysis

Photocatalysis—the process by which light drives chemical reactions—has long been hailed as a promising route toward clean energy and environmental remediation. Yet, the fine details of how these reactions unfold at the microscopic level, particularly at the interface between a solid catalyst and a liquid electrolyte, have remained elusive—until now.

In a groundbreaking study published in the Journal of the American Chemical Society, researchers led by Prof. Fan Fengtao and Prof. Li Can at the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences unveiled a novel method for directly measuring surface charges and electric fields at the nanoscale during photocatalytic reactions in liquid environments.

Cracking the Code of Charge Dynamics

Typically, photocatalysis unfolds in three stages: light absorption, charge separation and transfer, and chemical reaction. While previous research has heavily focused on charge transport within solid catalysts, the role of surface charges at the solid-liquid interface—where the actual reaction takes place—has been less understood, largely due to the difficulty of measuring such dynamics in situ.

To address this, the DICP team used a charged probe to isolate electrostatic interactions from other long-range forces. As a result, they were able to map the electric field distribution in the electrical double layer—a critical region at the catalyst-electrolyte interface. This breakthrough enabled the first direct measurements of surface potential and photovoltage under actual operating conditions.

A New Force Driving Reactions

One of the most significant findings was the identification of an additional driving force in photocatalytic reactions. Surface charges, the researchers found, actively pull photogenerated electrons toward the catalyst surface, thereby enhancing the efficiency of charge transfer and, consequently, the overall reaction rate.

Using BiVO₄ (bismuth vanadate) particles as a model catalyst, the team showed how changes in pH influence local surface potentials, offering micro- to nanoscale resolution. They linked these measurements to the rate of oxygen evolution reactions, confirming that surface electric fields induced by charge accumulation are key to improving reaction efficiency.

Visualizing the Full Charge Transfer Pathway

The team also successfully visualized the entire charge transfer journey—from the space charge region inside the semiconductor to the surface sites where the chemical reactions occur. As a result, they identified the optimal pH range for achieving effective spatial separation of electrons and holes, a critical requirement for high-performance photocatalysis.

A New Platform for Photocatalyst Design

“This imaging framework provides a powerful new platform to directly measure surface potential and reaction currents under realistic conditions,” said Prof. Fan. “It gives us a window into how photocatalytic reactions actually happen at the nanoscale.”

Prof. Li echoed the importance of the findings: “Our work offers valuable insights into one of the most persistent challenges in photocatalysis and opens new pathways for the design of more efficient photocatalysts and optimization of reaction environments.”

The Future of Clean Energy Catalysis

As the field of photocatalysis evolves, innovations like this are essential for unlocking its full potential—from artificial photosynthesis and solar fuel generation to water purification and green chemical manufacturing.

With this novel imaging approach, scientists now have a clearer lens on how quantum-level interactions influence real-world chemical transformations—bringing the world one step closer to harnessing light to power the future.

Read the Original Article: Phys.org

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