Defect Engineering in Photocatalytic Materials

Photocatalytic materials harness solar radiation to drive chemical transformations, offering pathways to sustainable energy conversion and environmental remediation. Central to this approach is the generation of electron–hole pairs within semiconductor structures, which can participate in reactions such as water splitting, carbon-dioxide reduction and pollutant degradation. However, the efficiency of most pristine semiconductors is constrained by a wide band gap that limits visible-light absorption and by rapid charge-carrier recombination that curtails reaction yields. Defect engineering has emerged as a powerful strategy to tune the electronic and surface properties of photocatalysts. By deliberately introducing vacancies, interstitials or dopants in the bulk or at the surface, researchers can modulate band edges, create mid-gap states and establish preferential pathways for charge separation. Sub-surface and surface defects can shift valence or conduction bands, narrow the band gap for enhanced light harvesting and serve as active sites for molecular adsorption and activation. Through precise control of defect type and concentration, materials such as titanium dioxide, bismuth oxide, carbon nitride and layered multinary nanosheets have shown marked improvements in hydrogen evolution, selective carbon fixation and organic synthesis. Defect engineering thus offers a versatile toolkit for optimising photocatalytic performance, bridging the gap between fundamental semiconductor physics and practical applications in renewable energy and green chemistry.

Research from Nature Portfolio

Recent studies have demonstrated that sub-10 nanometre rutile titanium dioxide nanoparticles with an abundance of surface and sub-surface defects can achieve state-of-the-art visible-light-driven water splitting. The engineered defects shift the valence band upward, narrowing the band gap while promoting charge separation, resulting in hydrogen production rates surpassing those of conventional titanium dioxide phases. In parallel, advances in bismuth oxide nanosheets reveal that oxygen vacancies confined within atomic layers significantly lower the adsorption energy of carbon dioxide, enabling single-electron transfer under mild conditions. Such vacancy-rich structures facilitate the photofixation of carbon dioxide to long-chain chemicals with near-quantitative selectivity, opening new routes for green carbon utilisation.

Defect Engineering in Photocatalytic Materials publication trend

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

Technical terms

Photocatalysis: A process in which a material absorbs light and generates electron–hole pairs that drive chemical reactions.

Band gap: The energy difference between the valence band and conduction band in a semiconductor, determining its light-absorption threshold.

Oxygen vacancy: A type of point defect formed by the absence of an oxygen atom in a metal oxide lattice, which can modify electronic properties.

Charge-carrier recombination: The process by which photogenerated electrons and holes annihilate each other, reducing catalytic efficiency.

Defect engineering: The deliberate introduction and control of imperfections in a material’s structure to tune its physical and chemical properties.

References

1. Sub-10 nm rutile titanium dioxide nanoparticles for efficient visible-light-driven photocatalytic hydrogen production. Nature Communications (2015).
2. Oxygen vacancy associated single-electron transfer for photofixation of CO2 to long-chain chemicals. Nature Communications (2019).
3. Structure‐Activity Relationship of Defective Metal‐Based Photocatalysts for Water Splitting: Experimental and Theoretical Perspectives. Advanced Science (2019).
4. Surface Modification of 2D Photocatalysts for Solar Energy Conversion. Advanced Materials (2022).
5. Atomically Thin 2D Multinary Nanosheets for Energy‐Related Photo, Electrocatalysis. Advanced Science (2018).