Photochemistry

Photochemistry encompasses all chemical processes initiated by the absorption of light. When a molecule absorbs a photon its electrons are promoted to excited states, opening pathways to bond cleavage, bond formation and energy transfer that are inaccessible by thermal means. These primary photochemical events—electronic excitation, intersystem crossing to triplet manifolds and radiative or non-radiative relaxation—can be followed by secondary processes such as radical generation, electron or energy transfer and catalytic cycles. In heterogeneous systems, light‐harvesting semiconductors drive surface redox reactions by generating electron–hole pairs whose separation and transfer to substrates underpin applications in solar fuel production, environmental remediation and synthetic chemistry. In homogeneous photoredox catalysis, visible‐light‐activated catalysts mediate single‐electron transfers to forge carbon–carbon or carbon–heteroatom bonds under mild conditions. The unique selectivity and mild reaction conditions afforded by photochemistry have transformed disciplines as diverse as materials science, organic synthesis and photodynamic therapy, enabling sustainable approaches to energy conversion, pollutant degradation and complex molecule assembly.

Research from Nature Portfolio

Ultrafast spectroscopy of In₂O₃/Nb₂O₅ S-scheme heterojunction nanofibres demonstrates sub-10 ps interfacial electron transfer and prolonged charge lifetimes that markedly enhance CO₂ photoreduction performance. Spatially selective photo-induced polymerisation of donor–acceptor networks has yielded hyper-cross-linked frameworks with giant intramolecular dipoles, achieving rapid exciton separation and record rates of H₂O₂ generation under visible light. A third advance employs gold-modified TiO₂/MoSₓ composites in which MoSₓ induces electron-deficient Auδ⁺ sites, strengthening O₂ adsorption and achieving H₂O₂ formation rates exceeding 30 mmol g⁻¹ h⁻¹. Density functional theory and spectroscopic studies confirm that electronic structure modulation at the Au interface is responsible for enhanced catalytic activity and selectivity.

Research from all publishers

Ni₂P-decorated CdS nanorods synthesised by in-situ solvothermal methods form core–shell heterojunctions with defined Schottky interfaces, boosting visible-light‐driven hydrogen evolution by more than twenty-fold and rivalling platinum-based systems in stability. Oxygen vacancy engineering at WO₃/In₂S₃ interfaces in S-scheme constructs triggers rapid charge‐transport channels and optimises both thermodynamic driving forces and kinetic barriers, delivering superior photocatalytic activity for solar fuel reactions. Two-dimensional CdS/covalent organic framework composites exploit S-scheme alignment to minimise charge diffusion distances and achieve high hydrogen evolution rates alongside selective oxidation of organic substrates, illustrating the versatility of heterojunction design in coupled redox processes.

Photochemistry publication trend

The graph below shows the total number of articles in photochemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Photocatalysis: Acceleration of a chemical reaction at the surface of a semiconductor upon light absorption, generating electron–hole pairs that mediate redox processes.

Photo-redox catalysis: Use of a light‐activated molecular catalyst to mediate single‐electron transfers under visible‐light irradiation, enabling selective bond construction or cleavage.

S-scheme heterojunction: Semiconductor–semiconductor interface with staggered band alignment that promotes directional charge separation and retains strong redox potentials.

Intersystem crossing (ISC): Non-radiative transition between electronic states of different spin multiplicity, typically from an excited singlet to a triplet state.

Schottky junction: Metal–semiconductor interface that establishes an internal electric field, suppressing electron–hole recombination and enhancing photocatalytic efficiency.

Reactive oxygen species (ROS): Highly reactive intermediates (e.g. •OH, O₂•–) generated under illumination that drive oxidative degradation of pollutants and mediating redox transformations.

Exciton: A bound electron–hole pair formed upon photoexcitation in a semiconductor or molecular material, whose diffusion and dissociation govern photophysical behaviour.

References

1. Ultrafast electron transfer at the In2O3/Nb2O5 S-scheme interface for CO2 photoreduction. Nature Communications (2024).
2. In-situ formatting donor-acceptor polymer with giant dipole moment and ultrafast exciton separation. Nature Communications (2024).
3. Enhancing photocatalytic H2O2 production with Au co-catalysts through electronic structure modification. Nature Communications (2024).
4. Fabrication of Ni2P Cocatalyzed CdS Nanorods with a Well-Defined Heterointerface for Enhanced Photocatalytic H2 Evolution. Catalysts (2022).
5. Oxygen Vacancies Trigger Rapid Charge Transport Channels at the Engineered Interface of S‐Scheme Heterojunction for Boosting Photocatalytic Performance. Angewandte Chemie International Edition (2024).
6. Bifunctional CdS/COF S-scheme photocatalyst for enhanced H2 evolution and organic synthesis. Chemical Engineering Journal (2023).