Photocatalytic CO₂ Reduction Using an Amorphous TiO₂-Encapsulated Cs₂AgBiBr₆ Nanocrystal: Selective Methane Formation

Abstract

Photocatalytic reduction of CO 2 is a promising strategy to alleviate the global energy crisis and environmental problems. Recently, metal halide perovskites with tunable bandgaps, large diffusion length, and abundant surface sites have drawn immense research interest for photocatalytic CO 2 reduction reactions. In this work, we develop an amorphous TiO 2 (aTiO 2 )encapsulated Cs 2 AgBiBr 6 double-perovskite nanocrystal (NC) by a room-temperature anti-solvent recrystallization method. Subsequently, we demonstrate the photocatalytic reduction of CO 2 to CH 4 (8.46 μmol g −1 h −1 ) and CO (5.72 μmol g −1 h −1 ) using this nanocomposite, where CH 4 is the dominant product. The Cs 2 AgBiBr 6 −aTiO 2 nanocomposite exhibits an 11-fold enhancement in the CH 4 yield compared to pristine Cs 2 AgBiBr 6 with prolonged stability of 16 h and higher selectivity of CH 4 over harmful CO production. The reason for the product selectivity is attributed to the presence of adventitious Ti 3+ on the surface of perovskite, which accelerates the CO 2 activation mechanism. The solvent effect on the product formation is also studied with ethyl acetate, acetonitrile, and dioxane. CH 4 becomes the dominant product in all of the cases, with an impressive evolution rate of 10.96 μmol g −1 h −1 in acetonitrile only. Impedance spectroscopy and ultrafast femtosecond transient absorption spectroscopy were used to establish the mechanism of CO 2 reduction. It was also confirmed that aTiO 2 helps in a faster and smoother charge transport at the interface by passivating the surface defects of the perovskite NCs. Our work provides a simple, highly efficient, and selective strategy for photocatalytic CO 2 reduction using doubleperovskite-based nanomaterial.

New Insights on Catalytic Valorization of Carbon Dioxide by Conventional and Intensified Processes

“…Acetonitrile led to the highest methane production among the three solvents, with a rate of 10.96 μmol g −1 h −1 . 304 Numerous studies have also investigated the use of photocatalysis to convert CO 2 into ethanol. Very recently, Shi et al also used polymeric carbon nitride for CO 2 photoreduction into ethanol, but unlike in ref 294, this time it was impregnated with indium−copper dual metal active sites.…”

Stacking Interactions and Photovoltaic Performance of Cs2AgBiBr6 Perovskite

“…Although Cs 2 AgBiBr 6 may not attain photovoltaic performance comparable to that of the Pb-based perovskites, [85,88,110,112] recent explorations of its photocatalytic properties have opened a new and promising area of application. [64,141,[192][193][194][195][196] Photocatalysis is an important chemical process, which can facilitate the [73] Copyright 2018, Wiley-VCH), b) with and without dye interlayer in a N 2 -filled glovebox, and c) with and without dye interlayer under ambient conditions (temperature: 20-30 °C; relative humidity: 30-40%). Reproduced with permission.…”

“…Several recent reports have also acknowledged this fact. [62][63][64][65] The crystal unit of Cs 2 AgBiBr 6 is a 3D perovskite framework with corner-shared octahedrons. [44] Cesium cation Cs þ occupies the cuboctahedral cavity, while Ag and Bi are octahedrally coordinated with Br À .…”

Emerging Single-Atom Catalysts and Nanomaterials for Photoelectrochemical Reduction of Carbon Dioxide to Value-Added Products: A Review of the Current State-of-the-Art and Future Perspectives

“…One alternative gaining a lot of focus worldwide is converting CO 2 into value-added products. There are numerous ways of transforming CO 2 to valuable products, viz., thermocatalysis, − biocatalysis, , radiolysis, , and photochemical (PC), − electrochemical (EC) − and photoelectrochemical (PEC) techniques. − The PC technique involves incorporating renewable solar energy for transforming CO 2 to produce valuable products. In contrast to the PEC process, it does not require any external potential bias and can be performed under ambient pressure and temperature conditions .…”

“…Hao et al incorporated an S-scheme heterojunction by synthesizing a CdS/Bi 2 WO 6 hybrid composite, which showed augmented PC operation, resulting in the evolution of 54.9 μmol g –1 and 4.8 μmol g –1 of CO and CH 4 , respectively . Employing double perovskite nanomaterial (NMT) such as Cs 2 AgBiBr 6 encapsulated with TiO 2 to fabricate the TiO 2 /Cs 2 AgBiBr 6 hybrid composite revealed excellent PC activity resulting in the formation of CO and CH 4 amounting to 5.72 μmol g –1 h –1 and 8.46 μmol g –1 h –1 , respectively . A hybrid composite consisting of keto-enamine covalent organic framework TpPa-1 combined with cobalt single atom Co-1T-MoS 2 to form a photocatalytic composite of TpPa-1/Co-1T-MoS 2 resulted in the formation of 196 μmol g –1 h –1 of CO .…”