A new photocatalytic strategy separates reactant activation from product release

Achieving both high efficiency and high selectivity remains a central challenge in catalytic hydrogenation reactions, as rapid reactant activation often leads to overly strong binding of intermediates and unwanted over-reduction. A new photocatalytic strategy now demonstrates how this long-standing trade-off can be overcome. By harnessing nonequilibrium charge carriers generated under visible light, the system promotes efficient hydrogen dissociation while steering the reaction toward selective semihydrogenation. Active hydrogen species migrate away from their formation sites to neighboring catalytic surfaces, where product formation and desorption are energetically favored. This spatial separation of reaction steps enables near-complete conversion under ambient conditions while maintaining excellent selectivity, offering a powerful new design principle for advanced catalytic systems.

Selective semihydrogenation of alkynes is a key industrial reaction for producing alkenes used in polymers, pharmaceuticals, and fine chemicals. However, conventional catalysts often suffer from a fundamental limitation: sites that efficiently activate hydrogen tend to bind reaction intermediates too strongly, increasing the risk of over-hydrogenation to alkanes. Existing strategies to balance activity and selectivity typically rely on complex catalyst modification or precise control of reaction conditions, which can limit scalability and robustness. In recent years, plasmonic photocatalysis has emerged as a promising route to drive reactions under mild conditions, yet its potential for resolving intrinsic catalytic trade-offs remains underexplored. Based on these challenges, it is necessary to develop new catalytic strategies that decouple hydrogen activation from selective product formation.

In a study published (DOI: 10.1016/j.esci.2025.100481) online on March 2026, in eScience, researchers from Nankai University, Dalian Maritime University, and collaborating institutions report a light-driven antenna–reactor photocatalyst that achieves highly efficient alkyne semihydrogenation under ambient conditions. The work demonstrates that nonequilibrium charge carriers generated by plasmonic gold nanoparticles can trigger hydrogen spillover from isolated palladium atoms to neighboring gold surfaces. This mechanism enables nearly complete conversion of phenylacetylene with high selectivity toward styrene at room temperature and atmospheric pressure.

The researchers constructed a photocatalyst that integrates palladium single atoms anchored on carbon nitride with plasmonic gold nanoparticles, forming a spatially decoupled antenna–reactor architecture. Under visible light illumination, gold nanoparticles act as optical antennas, generating nonequilibrium charge carriers through plasmon decay. These energetic carriers significantly enhance hydrogen dissociation at palladium single-atom sites, even under mild conditions.

Using in situ surface-enhanced Raman spectroscopy, the team directly observed the migration of active hydrogen species from palladium sites to adjacent gold surfaces—a phenomenon known as hydrogen spillover. This migration plays a critical role in controlling reaction selectivity. While palladium efficiently activates hydrogen, gold provides a surface where alkynes can be selectively converted to alkenes with weaker binding, facilitating rapid product desorption and suppressing over-hydrogenation.

Catalytic tests showed that the system achieved nearly 100% conversion of phenylacetylene with around 90% selectivity toward styrene at 298 K and atmospheric pressure, outperforming conventional noble-metal catalysts. Density functional theory calculations further revealed that the key hydrogenation step proceeds with lower energy barriers on gold surfaces, confirming the advantage of separating hydrogen activation from product formation. Together, these results demonstrate a general strategy for breaking the activity–selectivity trade-off through spatial and energetic decoupling.

"This work provides compelling evidence that catalytic performance can be fundamentally improved by separating where key reaction steps occur," said one of the corresponding authors. "Instead of forcing a single active site to satisfy conflicting requirements, we allow hydrogen activation and selective hydrogenation to take place on different components of the catalyst. The involvement of nonequilibrium carriers adds an additional level of control that is difficult to achieve in conventional thermal catalysis, opening new opportunities for light-driven chemical transformations."

The proposed antenna–reactor strategy offers a versatile blueprint for designing next-generation catalysts that operate efficiently under mild conditions while maintaining high selectivity. Beyond alkyne semihydrogenation, this approach could be extended to a wide range of hydrogenation and redox reactions where competing reaction pathways limit performance. By combining single-atom catalysis, plasmonic effects, and hydrogen spillover, the study highlights how light energy can be converted into precise chemical control rather than simple heating. Such advances may contribute to more energy-efficient chemical manufacturing, reduced reliance on harsh reaction conditions, and the development of sustainable catalytic technologies for the chemical industry.

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Contact the author:

Name: Editorial Office of eScience

Email: eScience@nankai.edu.cn

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