Interfacial Reaction-Induced Defect Engineering: Enhanced Visible and Near-Infrared Absorption of Wide Band Gap Metal Oxides with Abundant Oxygen Vacancies

Abstract

Modified metal oxides with narrow band gaps have attracted great interest in photothermal applications because of their wide optical absorption range. To tune wide band gap metal oxides into visible and near-infrared responsive materials, we deploy a unique interfacial reaction-induced defect engineering approach, which enables us to effectively modify the electronic structure of metal oxides by introducing oxygen vacancy defects. This approach reduced the band gap of zirconia from 5.47 to 1.38 eV, accompanied by a color change to black. More importantly, it is not limited by the size of the metal oxides, and bulk black zirconia was successfully obtained for the first time. It has been demonstrated that the prepared black zirconia can be applied as an effective photothermal therapy agent in vitro. Additionally, the interfacial reaction-induced defect engineering approach has been successfully extended to enhance the optical absorption of other metal oxides.

Blackening Mechanism and Mechanical Properties Variation of Zirconia Ceramic Induced by Active Metal Brazing

“…Under this circumstance, the observed blackening phenomenon of ZrO 2 is reasonably attributed to the interfacial reaction between ZrO 2 and Ti, which is in line with our previous report. [ 24 ] In addition to the formation of reaction layers adjacent to the ceramic substrate, the Ti substrate is dissolved into liquid filler to form the Ti x (Cu, Pd) y compounds and α‐Ti + Ti 2 Pd phases nearby the titanium alloy. Additionally, the formation of the above chemical compounds in the brazing joint ensures the high‐quality metallurgical bonding of ZrO 2 /Ti brazing joints.…”

“…Moreover, we found that there are two important steps in the interfacial reaction process (Figure 5b), which are oxygen dissolved in titanium and oxygen diffusion in ZrO 2 . [24] To implement these two steps, a well-contacted ZrO 2 /Ti interface and a high-temperature environment are necessary. Compared to the previous method of preparing nano-sized black ZrO 2 at relatively low temperature, [18,22] the high temperature employed in this method greatly accelerates the diffusion of oxygen ions in ZrO 2 , leading to the preparation of black ZrO 2 with large sizes.…”

One-step synthesis of black TiO2-x microspheres by ultrasonic spray pyrolysis process and their visible-light-driven photocatalytic activities

“…S3 , the band gap of the WTM-900 was 3.05 eV. On the other hand, the BTM-900 displayed two-part of the slope, in which the relatively small band gap energy of 2.82 eV is ascribed to the intermediate band formed below the conduction band and the large band gap of 3.22 eV is attributed to the intrinsic band gap of TiO 2 [25] , [31] , [32] , [33] . The photoluminescence (PL) spectrum of BTM-900, shown in Fig.…”

Control of monomeric Vo’s versus Vo clusters in ZrO2−x for solar-light H2 production from H2O at high-yield (millimoles gr−1 h−1)

“…Strategies to ameliorate photocatalytic ZrO 2 activity, can include: (i) heteroatom insertion 12 – 17 into ZrO 2 crystal, or (ii) Oxygen-defects’ creation 18 – 23 . The influence of heteroatoms in ZrO 2 has been investigated 12 – 17 , in photocatalytic dye degradation or O 2 evolution.…”

“…Without heteroatom doping, generation of reduced states in reducible metal-oxides, such as TiO 2 , are decisively beneficial for H 2 photo yield. Examples include the work of Mao et al 23 , Naldoni et al 26 and our Flame Spray Pyrolysis (FSP)-made black TiO 2−x 27 . ZrO 2 is a notoriously non-reducible oxide 28 , 29 , since introduction of Vo’s into the ZrO 2 lattice is not favored energetically 8 , 15 – 20 , thus specific synthesis methods are needed to achieve reduction of the ZrO 2 lattice.…”