Charge Carrier Dynamics of CsPbBr₃/g-C₃N₄ Nanoheterostructures in Visible-Light-Driven CO₂-to-CO Conversion

Abstract

The photon energy-dependent selectivity of photocatalytic CO 2 -to-CO conversion by CsPbBr 3 nanocrystals (NCs) and CsPbBr 3 /g-C 3 N 4 nanoheterostructures (NHSs) was demonstrated for the first time. The surficial capping ligands of CsPbBr 3 NCs would adsorb CO 2 , resulting in the carboxyl intermediate to process the CO 2 -to-CO conversion via carbene pathways. The type-II energy band structure at the heterojunction of CsPbBr 3 /g-C 3 N 4 NHSs would separate the charge carriers, promoting the efficiency in photocatalytic CO 2 -to-CO conversion. The electron consumption rate of CO 2 -to-CO conversion for CsPbBr 3 /g-C 3 N 4 NHSs was found to intensively depend on the rate constant of interfacial hole transfer from CsPbBr 3 to g-C 3 N 4 . An in situ transient absorption spectroscopy investigation revealed that the half-life time of photoexcited electrons in optimized CsPbBr 3 /g-C 3 N 4 NHS was extended two times more than that in the CsPbBr 3 NCs, resulting in the higher probability of charge carriers to carry out the CO 2 -to-CO conversion. The current work presents important and novel insights of semiconductor NHSs for solar energy-driven CO 2 conversion.

Nitrogen Configuration Effects on Charge Carrier Dynamics in CsPbBr3/Carbon Dots S-Scheme Heterojunction for Photocatalytic CO2 Reduction

“…In addition, the NCDs were in direct contact with CPB NCs to form the heterojunctions. Furthermore, the XRD patterns of CPB/H-NCDs and CPB/M-NCDs were a close match to the mixed-phase crystal structure of monoclinic and cubic CPB NCs, as shown in Figures c and d . Note that the greater crystallinity of CPB/M-NCDs than CPB/H-NCDs can also be observed in the XRD spectra.…”

“…The accumulated charge carriers on the CB and VB or in the trap states of the photocatalysts involving CO 2 -to-CO conversion in the microsecond time scale is monitored in this system. The transient bleach (TB, ground-state depletion) signal from 400 nm to 600 nm was detected, which can be attributed to the photogenerated electrons on the CB or trap states of CPB NCs . A higher intensity of TB signal for CPB/H-NCDs and CPB/M-NCDs than that for CPB is observed, which confirm that the S-scheme CPB/NCDs NHSs exhibit the remarkable separation performance.…”

“…CsPbBr 3 (CPB), combined with two-dimensional (2-D) carbon materials to form nanoheterostructures (NHSs) such as CPB/graphene oxide (GO), CPB/few-layer graphene (FLG), and CPB/g-C 3 N 4 , has been studied for its efficacy in photocatalytic CO 2 reduction. − Studies have also been carried out on the effects of charge carrier dynamics at the heterojunction of CPB NHSs on the performance of photocatalytic CO 2 reduction. For instance, Chen et al reported that the CPB/GO and CPB/FLG NHSs could establish a type-II band structure and a Schottky heterojunction, respectively, at their interfaces .…”

“…The distinct energy band structure at the heterojunctions of CPB/GO and CPB/FLG NHSs led to the accumulation of photogenerated electrons at the various energy states, resulting in varied chemical potentials toward CO 2 reduction. Conversely, CPB/g-C 3 N 4 NHSs have shown promise as photocatalysts for CO 2 reduction. , Ou et al ingeniously embedded CPB nanocrystals (NCs) into porous g-C 3 N 4 (PCN) with abundant amino/imino groups. The N–Br bonds between CPB NCs and PCN could facilitate charge separation, to prolong carrier lifetime and simultaneously enhance photocatalytic CO 2 reduction activity.…”

All-inorganic lead halide perovskites for photocatalysis: a review

“… 233,234 China is supposed to reach a “carbon peak” by 2030, 235 indicating that greenhouse gas emissions play an important role in environmental issues,; thus, photocatalytic reduction of CO 2 is considered the most promising method. 236–239 Due to their outstanding qualities, such as affordability, simplicity of the synthesis method, visible light absorption, high CO 2 adsorption surface area, and adjustable structure, all-inorganic lead halide perovskites have been proved as effective catalysts. 240–246 The all-inorganic lead-halide perovskite materials generate electron–hole pairs by absorbing solar energy, and the generated electrons can reduce CO 2 to high value-added chemicals such as CO, 247 CH 4 , 248 CH 3 OH, 249 HCHO, 250 HCOOH, 196 and C 2 H 4 .…”