Boosting Photocatalytic Activity and Stability of Lead-Free Cs₃Bi₂Br₉ Perovskite Nanocrystals via In Situ Growth on Monolayer 2D Ti₃C₂T_x MXene for C–H Bond Oxidation

Abstract

Light-driven selective oxidation of saturated C–H bonds with molecular oxygen, as an alternative to conventional thermochemical catalysis, allows a sustainable and eco-friendly manner to convert solar energy into highly value-added oxygenates. However, the photocatalytic oxidation of hydrocarbons still remains a great challenge owing to the low efficiency in the separation and transfer of photogenerated charge of the currently available photocatalytic materials. Herein, we report a novel perovskite-based heterostructure photocatalyst, in which ligand- and lead-free all-inorganic perovskite Cs3Bi2Br9 nanocrystals (NCs) with uniform crystal size and high crystallinity were homogeneously distributed on the surface of ultrathin two-dimensional (2D) monolayer Ti3C2T x MXene nanosheets in an in situ growth manner. The resultant heterostructure featured with intimate interface between Cs3Bi2Br9 NCs and Ti3C2T x MXene and strong visible-light adsorption not only exhibits significant enhancement in the performance of photocatalytic oxidation of challenging aromatic and aliphatic alkanes under visible-light irradiation but also greatly improves the stability of Cs3Bi2Br9 NCs under a reaction environment. Comprehensive characterizations reveal that the formation of an intimate interface between Cs3Bi2Br9 NCs and highly conductive ultrathin 2D Ti3C2T x MXene nanosheets via strong interaction markedly accelerates the separation and transfer efficiency of photogenerated electron–hole pairs and simultaneously suppresses their recombination, resulting in improved utilization of the excited charges, which account for the highly enhanced photocatalytic performance.

Coexistence of Fe Nanoclusters Boosting Fe Single Atoms to Generate Singlet Oxygen for Efficient Aerobic Oxidation of Primary Amines to Imines

“…•− or OH • in the reaction system. When the reaction was performed in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO), or 2,6-di-tert-butyl-4-methylphenol (BHT), as a scavenger to any involved radicals including carbon-centered radicals, 20 no change in both activity and selectivity was observed, further suggesting a nonradical-mediated nature. In sharp contrast, a considerable decrease in activity was observed when NaN 3 or β-carotene, a typical scavenger for the singlet oxygen 1 O 2 , 19a,21 was added into the reaction, indicating that 1 O 2 primarily engages in the reaction.…”

MXene-Based Photocatalysts and Electrocatalysts for CO2 Conversion to Chemicals

“…Higher electrical conductivity was also found in the low addition of Ti 3 C 2 T x MXene, compared to the addition of other 2D nanomaterials, such as MoS 2 , which contributed to higher catalytic activity [54]. Several reports have also shown the combination of MXenes with other photocatalyst materials, such as g-C 3 N 4 [53], perovskite materials (Cs 3 Bi 2 Br 9 , FAPbBr 3 , CsPbBr 3 , and Cs 2 AgBiBr 6 ) [56][57][58][59], layered double hydroxides (NiAl, Co-Co, and Co 2 Al 0.95 La 0.05 ) [60][61][62], Bi-based photocatalysts (BiOX (X = Cl, Br, I), Bi 2 XO 6 (X = W, Mo), and hybrid Bi 2 O 2 SiO 3 ) [50,63,64], and metal oxides and metal sulfides (TiO 2 , CeO 2 , InVO 4 , CdS, Cd 0.2 Zn 0.8 S, and ZnIn 2 S 4 ) [9,49,53,[65][66][67][68][69].…”

Recent Advances in Lead-Free Halide Perovskites for Photocatalysis

“…The formed Cs 3 Bi 2 Br 9 adopts a 2D corrugated structure composed of corner-sharing [BiBr 6 ] 3– octahedra, and it has an increased bandgap ( E g = 2.62 eV), compared with Cs 3 Bi 2 I 9 . Cs 3 Bi 2 Br 9 has been widely investigated in the field of photocatalysis, due to its environmental friendliness and superior chemical stability. ,,,, …”

“…However, the introduction of noble metals increases the cost of the photocatalysts. To overcome such limitations, 2D nanomaterials, such as reduced graphene oxide (RGO), nitrogen-doped carbon (N–C), and MXenes, can also serve as co-catalysts to enhance the photocatalytic performance of LFHPs. ,,, …”