Novelty All‐Inorganic Titanium‐Based Halide Perovskite for Highly Efficient Photocatalytic CO₂ Conversion

Abstract

Lead halide perovskite materials have great potential for photocatalytic reaction due to their low fabrication cost, unique optical absorption coefficient, and suitable band structures. However, the main problems are the toxicity and instability of the lead halide perovskite materials. Therefore, a facile synthetic method is used to prepare lead‐free environmentally friendly Cs2TiX6(X = Cl, Cl0.5Br0.5, Br) perovskite materials. Their structural and optical characteristics are systematically investigated. The band gaps of the produced samples are illustrated to be from 1.87 to 2.73 eV. Moreover, these materials can keep high stability in harsh environments such as illumination and heating, and the Cs2Ti(Cl0.5Br0.5)6 microcrystals demonstrate the yields of 176 µmol g−1 for CO and 78.9 µmol g−1 for CH4 after light irradiation for 3 h, which is of the first report of Ti‐based perovskite photocatalysts. This finding demonstrates that the Ti‐based perovskites will create opportunities for photocatalytic applications, which may offer a new idea to construct low‐cost, eco‐friendly, and bio‐friendly photocatalysts.

Perovskite Paradigm Shift: A Green Revolution with Lead-Free Alternatives in Photocatalytic CO2 Reduction

“…249−251 For example, the mixed halide approach was employed on the all-inorganic Ti-based (Cs 2 TiX 6 ) halide perovskites for enhanced visible light absorption, reduced radiative recombination, and efficient charge carrier transportation. 149 Consequently, the Cs 2 Ti-(Cl 0.5 Br 0.5 ) 6 microcrystals accomplished higher CO and CH 4 yields of 58.7 and 26.3 μmol g −1 h −1 , respectively, which are much higher than obtained with the single halide counterparts. This straightforward strategy was also utilized on the Te-based (Cs 2 TeX 6 ), 148 Cu-based (CsCuX 3 ), 170 and Bi-based (Cs 3 Bi 2 X 9 ) 252 perovskites as well as the Cs 2 AgBiX 6 double perovskites, 145 in which the mixed halide perovskites were shown to exhibit better performance than the single halide perovskites.…”

“…Conduction and valence band positions of several reported all-inorganic LFHP photocatalysts with the relative potential in photocatalytic CO 2 reduction. The band levels are acquired from published results. ,,− …”

Lead‐Free Halide Perovskite Photocatalysts for Photocatalytic CO2 Reduction: A Review

“…Zhou et al prepared lead‐free titanium halide perovskite Cs 2 TiX 6 (XCl, Cl 0.5 Br 0.5 , Br) nanocrystals. [ 120 ] Compared with Cs 2 TiCl 6 , Cs 2 Ti(Cl 0.5 Br 0.5 ) 6 broadens the light response range, but it preserves the reducibility of electrons in the CB. In addition, the mobility of photogenerated carriers is also improved.…”

“…[119] The UVÀvis absorption spectra of CsCuCl , Br) nanocrystals. [120] Compared with Cs 2 TiCl 6 , Cs 2 Ti(Cl 0.5 Br 0.5 ) 6 broadens the light response range, but it preserves the reducibility of electrons in the CB.…”

Mixed-Cation Vacancy-Ordered Perovskites (Cs2Ti1–xSnxX6; X = I or Br): Low-Temperature Miscibility, Additivity, and Tunable Stability

“…Beyond photovoltaic applications, the A 2 BX 6 structural family exhibits features associated with both zero-dimensional and three-dimensional materials (such as low thermal conductivity, high compressibility, and strong exciton binding despite relatively small electronic band gaps), − which makes them potential candidates for a range of alternative applications, such as potential thermoelectric materials, white-light emitters/phosphors, , photocatalysts, high-entropy semiconductors and more, as well as offering a highly tunable playground to study physical phenomena associated with strong Frenkel excitons. − Moreover, these materials have been reported to show nonlinear optical activity, being in fact the only known third harmonic generation (THG)-active lead-free perovskite structures …”