LI Zhenzi， WANG Pei， RUAN Zhongwang， ZHOU Wei

College of Chemistry and Chemical Engineering， Qilu University of Technology （Shandong Academy of Sciences）， Jinan 250353， China

Received: 2025-07-05, Revised: 2025-11-17, Online: 2026-01-19.

Abstract

Significance To systematically address the severe environmental degradation and energy scarcity stemming from rapid global industrialization and urbanization in the 21st century， the development of highly efficient， clean， and sustainable energy technologies has become an urgent imperative. This field of research focuses on employing advanced defect engineering strategies to achieve precise electronic and structural modulation of titanium dioxide （TiO₂） photocatalytic nanomaterials. The primary goal is to overcome the inherent limitations of pristine TiO₂： 1） its wide bandgap （about 3.2 eV）， which confines light absorption mainly to the ultraviolet region （about 5% of the solar spectrum）， 2） the rapid recombination （on the nanosecond timescale） of photogenerated electron-hole pairs， which leads to low quantum efficiency. The ultimate objective is to establish a solid material foundation and theoretical framework for the large-scale and practical application of defective TiO₂ in critical energy and environmental technologies. These include the highly efficient degradation of pollutants， solar-driven hydrogen production via water splitting， photocatalytic reduction of carbon dioxide （CO₂） to fuels， and nitrogen fixation to ammonia under mild conditions.Progress This review systematically summarizes the recent research progress and emerging trends in defective TiO₂ photocatalytic nanomaterials. First， it provides a comprehensive overview of the mainstream strategies for introducing defects， including hydrogenation reduction， chemical reduction （e.g.， using NaBH₄）， high-energy particle irradiation （e.g.， plasma， electron beams）， electrochemical reduction， and chemical oxidation methods. A comparative analysis of these methods is conducted， highlighting their respective advantages and limitations in terms of the types of defects introduced （e.g.， oxygen vacancies， Ti³⁺ species， surface disordered layers）， the uniformity of defect concentration and distribution， process controllability， energy consumption， cost， and potential for future scalable application. Second， the intrinsic physicochemical mechanisms by which defect states enhance the photocatalytic performance of TiO₂ are elucidated： 1） Defects introduce mid-gap states within the material’s bandgap， effectively narrowing its apparent width and thereby significantly extending light absorption range from the UV into the visible and even near-infrared regions.2） These defect sites， particularly oxygen vacancies， act as efficient trapping centers for photogenerated electrons， markedly suppressing the recombination kinetics of electron-hole pairs， effectively prolonging charge carrier lifetimes， and consequently allowing more carriers to participate in surface catalytic reactions. 3） Simultaneously， defect sites serve as highly active surface centers， significantly promoting the adsorption and activation of key reactant molecules such as H₂O， CO₂， and N₂， and effectively lowering their reaction energy barriers. Special emphasis isplaced on the evolution of the field， which has progressed from the initial introduction of single defects towards the design and construction of synergistic multi-defect systems. For instance， the combination of nitrogen doping with oxygen vacancies creates a notable synergistic effect.It optimizes the electronic band structure， generates complementary active sites， and significantly enhances visible-light-driven hydrogen evolution performance. Substantial experimental evidence demonstrates that defective TiO₂， exemplified by the remarkable “black TiO₂” with its broad-spectrum absorption， exhibits exceptional photocatalytic performance across several domains. It enables highly efficient degradation of organic dyes and pharmaceutical pollutants under visible light irradiation.The material achieves orders-of-magnitude enhancement in hydrogen production rates， even without noble metal co-catalysts （with optimal rates reaching 43 mmol/（g·h）.It also demonstrates high selectivity for hydrocarbon fuels such as methane during CO₂ photoreduction （e.g.， CH₄ production rates of 115 μmol/（g·h）.Notably， defective TiO₂successfully accomplishes photocatalytic conversion of N₂ and H₂O directly to NH₃under ambient temperature and pressure.These advantages offer a sustainable and potentially revolutionary alternative to the traditional， energy-intensive Haber-Bosch process.

Conclusions and Prospects Defective TiO₂ undoubtedly represents a significant milestone in the design of photocatalytic materials. However， its transition from laboratory research to practical， large-scale application still faces a series of critical challenges. The main existing problems are outlined as follows.1） Achieving precise and reproducible control over defect structures at the atomic and nanoscale remains exceedingly difficult.No standard has been established for defining an “ideal” defect configuration （including type， density， and spatial distribution） for specific catalytic reactions.2） Many reported high-performance synthesis methods struggle to meet the demands of industrial-scale production due to issues such as energy consumption， cost， and process complexity.Moreover， the chemical and structural stability of these metastable defect structures under harsh operational conditions （e.g.， prolonged strong illumination， high temperatures， or oxidative environments） still requires thorough validation. 3） Conventional ex situ characterization techniques are inadequate for capturing the dynamic evolution of defect states and their interactions with reaction intermediates in realtime during catalysis， limiting the in-depth analysis of the life-cycle dynamics of charge carriers.Based on these challenges， this review argues that future research should concentrate on the following core directions： 1） The primary task is to develop simpler， greener， cost-effective， and easily scalable synthesis techniques， while ensuring the long-term stability of the introduced defects under operational conditions. 2） It is imperative to promote the deep integration of advanced in situ/operando characterization techniques， such as synchrotron-based X-ray absorption spectroscopy， environmental transmission electron microscopy， in situ infrared spectroscopy， and positron annihilation spectroscopy， with theoretical calculations （e.g.， density functional theory）. This integrated approach is essential for dynamically tracking the evolution of defects under realistic reaction conditions， clarifying their mechanistic roles as active centers， and mapping the kinetics of charge carrier separation， migration， and recombination. The goal is to establish accurate “structure-property-performance” correlation maps， laying a solid foundation for the rational design of next-generation photocatalysts. 3） Effortsshould be made to expand the application boundaries of defective TiO₂， leveraging its unique physicochemical properties in emerging interdisciplinary fields such as energy storage （e.g.， lithium-ion batteries， supercapacitors）， high-sensitivity chemical sensing， and biomedicine （e.g.， photothermal therapy， antibacterial materials）.This expansion will open new research paradigms and market opportunities. Through sustained and deepened interdisciplinary collaboration among chemistry， materials science， physics， and engineering， defective TiO₂ nanomaterials hold immense potential to transition from model systems in fundamental research into scalable technological solutions capable of addressing practical energy and environmental problems， making an indispensable contribution to building a sustainable future for humanity.

Keywords： photocatalysis； titanium dioxide； defect regulation； nanomaterial

Get Citation:LI Zhenzi， WANG Pei， RUAN Zhongwang， et al. Research progress on preparation and photocatalytic application of defective TiO₂ photocatalytic nanomaterials［J］. China Powder Science and Technology， 2026， 32（3）： 1-17.

Funding： The research was supported by the National Natural Science Foundation of China (Grant No. 52172206), the Key R&D Program of Shandong Province (Grant No. 2024TSGC0121), and the Scientific Research-Education Integrated Talent Cultivation Project of Qilu University of Technology (Shandong Academy of Sciences) (Grant No. 2024RCKY018).

DOI：10.13732/j.issn.1008-5548.2026.03.005

CLC No: O614； TB4            Type Code: A

Serial No:1008-5548（2026）03-0001-17