In Situ Growth of Lead-Free Cs₂CuBr₄ Perovskite Quantum Dots in KIT-6 Mesoporous Molecular Sieve for CO₂ Adsorption, Activation, and Reduction

Abstract

Metal halide perovskites (MHPs) are emerging as promising candidates for photocatalytic CO2 conversion. However, their practical application is still restricted by the poor intrinsic stability and weak adsorption/activation toward CO2 molecules. The rational design of MHPs-based heterostructures with high stability and abundant active sites is a potential solution to this obstacle. Herein, we report the in situ growth of lead-free Cs2CuBr4 perovskite quantum dots (PQDs) in KIT-6 mesoporous molecular sieve, obtaining remarkable photocatalytic CO2 reduction activity and durable stability. The optimized Cs2CuBr4@KIT-6 heterostructure exhibits the photocatalytic CO and CH4 evolution rates of 51.6 and 17.2 μmol g–1 h–1, respectively, far exceeding those of pristine Cs2CuBr4. On the basis of in situ diffuse reflectance infrared Fourier transform spectra and theoretical investigations, the detailed CO2 photoreduction pathway is systematically revealed. This work provides a new route for the rational construction of perovskite-based heterostructures with strong CO2 adsorption/activation and good stability for photocatalytic CO2 reduction.

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

“…In practice, the rational selection of encapsulation material and precise tuning of encapsulation thickness are paramount to ensure that the light absorption, mass transfer, and charge migration properties remain unaffected by the protective layer. In light of this concept, several encapsulation materials such as mesoporous silica, ,, MOFs, ,, and metal oxides ,,, have been explored for LFHPs.…”

“…However, careful selection of capping materials and encapsulation technique is paramount as adverse effects such as limited light penetration, restricted reactants permeability and inefficient charge transfer due to weak interface contact may arise otherwise. Nevertheless, to date, there are limited reports on the encapsulation of LFHPs for enhanced CO 2 reduction activity and stability, with molecular sieves primarily employed as the encapsulation material. ,, Porous MOFs and COFs which are universally used for enveloping lead halide perovskites may also be effective for LFHPs. , The major reasons lie in their large surface areas and abundant pores for copious active sites as well as commendable light harvesting from light reflection and scattering within pores. Therefore, the development of new compatible encapsulation materials, such as porous semiconductor networks, monodispersed capping agents, or semiconducting polymers of suitable chemical interactions, band energy, and structure holds substantial promise in advancing this field.…”

Lead‐Free Perovskite‐Based Photocatalysts for Solar‐Driven Chemistry Technologies

“…The key steps in CO 2 conversion include light absorption, charge separation, surface reactions, and the formation of carbon‐based products like carbon monoxide (CO), hydrocarbons or another kind of organic functionalities as added‐value chemicals. Like H 2 production, a suitable photomaterial is required to generate photocarriers, favoring the electron accumulation in the CB, also considering the band alignment to trigger the CO 2 reduction [68] …”

Regulating Oxygen Vacancies and Fermi Level of Mesoporous CeO2‐x for Intensified Built‐In Electric Field and Boosted Charge Separation of Cs3Bi2Br9/CeO2‐x S‐Scheme Heterojunction

“…Previous reports demonstrated that the confinement of perovskite nanocrystals in a mesoporous martrix can effectively protect them from aggregation, thus enhancing their photocatalytic stability. [35][36][37] Moreover, the unique mesoporous structure can afford a large specific surface area and abundant active sites, which can simultaneously promote CO 2 adsorption and activation. To construct an efficient S-scheme heterojunction with a large BEF intensity and strong CO 2 adsorption capability, selecting an appropriate semiconductor matrix with a regulable E F is critical.…”