A large variety of reduced titanium dioxide (TiO_2-x) materials have been reported recently. Reduced TiO₂, usually resulting from the removal of oxygen atoms or hydrogen incorporation, is proved to be efficient for achieving highly photocatalytic performance including photodegradation of organic compounds, hydrogen generation from water splitting, CO₂ reduction for CH₄ evolution, solar cells, etc. To further improve the properties and activities of TiO_2-x, a combination of the Ti³⁺ self-doping and other traditional modifications like nonmetals doping has been proposed in the past decades. This paper provides a general and critical review on the further modifications on reduced TiO₂ samples, including non-metal elements (N, B, S, F and I) doping, noble-metal (Au, Pt, Pd and Ag) and iron-group metal (Fe, Co and Ni) grafting, metal oxide compositing, carbon (nanotubes and graphene) and carbon-based-material compositing, special facets exposure (mainly dual {001}-{101} and {111}-{110} facets) of TiO_2-x and ordered structure controlling of TiO_2-x. These modifications enhance the physical and/or chemical properties of the reduced TiO₂, or create new features for the modified TiO_2-x samples, which finally leads to the enhancement of photocatalytic performance. Key examples such as N-doping, Au grafting and graphene-based compositing are discussed carefully, and the mechanisms for solar light enhancement, electron transfer and charge separation are also investigated. Finally, some challenging issues on TiO_2-x catalysts are also proposed to encourage new approaches for preparation of TiO_2-x catalysts with efficiently photocatalytic performance.

最近已经报道了多种还原的二氧化钛（TiO _2-x）材料。TiO _2的还原通常是由于氧原子的去除或氢的掺入而引起的，已被证明可有效实现高光催化性能，包括有机化合物的光降解，水分解产生的氢，CH ₄析出的CO ₂还原，太阳能电池等。。为了进一步改善TiO _2-x的性能和活性，Ti ³⁺的组合在过去的几十年中已经提出了自掺杂和其他传统的修改方法，例如非金属掺杂。本文对还原的TiO ₂样品的进一步修饰提供了一般性和严格的综述，包括非金属元素（N，B，S，F和I）掺杂，贵金属（Au，Pt，Pd和Ag）和铁组金属（Fe，Co和Ni）接枝，金属氧化物复合，碳（纳米管和石墨烯）和碳基材料复合，特殊刻面暴露（主要是{001}-{101}和{111}-{110双重） }的TiO刻面）_2-X和有序结构控制的TiO _2-X 。这些修饰增强了还原后的TiO ₂的物理和/或化学性质，或为修饰的TiO _2-x创建了新的特征。样品，最终导致光催化性能的增强。仔细讨论了诸如N掺杂，Au接枝和石墨烯基复合等关键例子，并研究了增强太阳光，电子转移和电荷分离的机理。最后，还提出了一些有关TiO _2-x催化剂的挑战性问题，以鼓励采用新方法制备具有有效光催化性能的TiO _2-x催化剂。