Unveiling Charge-Separation Dynamics in CdS/Metal–Organic Framework Composites for Enhanced Photocatalysis

Abstract

Photocatalytic water splitting for H2 production becomes one of the most favorable pathways for solar energy utilization, while the charge-separation dynamics in composite photocatalysts is largely elusive. In the present work, CdS-decorated metal–organic framework (MOF) composites, namely, CdS/UiO-66, have been synthesized and exhibit high H2 production activity from photocatalytic water splitting, far surpassing the MOF and CdS counterparts, under visible light irradiation. Transient absorption (TA) spectroscopy has been adopted in this report to unveil the charge-separation dynamics in CdS/UiO-66 composites, a key process that dictates their function in photocatalysis. We show that, in addition to the preferable formation of fine CdS particles assisted by the MOF, effective electron transfer, which occurs from excited CdS to UiO-66, significantly inhibits the recombination of photogenerated charge carriers, ultimately boosting the photocatalytic activity for H2 generation. This report on charge-separation dynamics for CdS–MOF composites affords significant insights for future fabrication of advanced composite photocatalysts.

In-situ incorporation of Copper(II) porphyrin functionalized zirconium MOF and TiO2 for efficient photocatalytic CO2 reduction

“…5), all nanocomposites show superior photoactivity rather than the pure TiO 2 mainly due to a synergistic effect between TiO 2 and CTU, i.e., consistent augment of light absorption as well as combination between MOF and TiO 2 , both of which will be elaborately demonstrated in mechanism as given below. In addition, the enhanced dispersion of TiO 2 NPs by MOF is also able to prevent TiO 2 particle from aggregation and consequently provide additional exposed surface reaction sites [6,34]. Hence, when the amount of CTU in the composite is fixated, the catalytic activity can be continuously improved along with increasing the amount of the loaded primary catalyst, TiO 2 (Fig.…”

“…UiO-66, a typical MOF with the chemical formula of Zr 6 SBUs (Zr 6 O 4 (OH) 4 ), possesses satisfactory stability and is regarded as a potential photocatalyst. It is, however, generally incapable of accepting electrons from the BDC linker under light irradiation, because the redox potential energy level of the Zr 6 SBUs in UiO-66 lies above the LUMO of the BDC ligands and consequently lowers the electron accepting levels [6,7]. In order to engender new energy levels in the band structure, mixed ligand MOFs have been studied, and subsequently playing an essential role in the realization of MOFs' potential within a wide range of applications [8].…”

Efficient photoredox conversion of alcohol to aldehyde and H2 by heterointerface engineering of bimetal–semiconductor hybrids

“…[6][7][8][9][10] Integrating different functional materials into a single hybrid structure with precise design holds great promise for constructing efficient composite photocatalysts owing to the synergistic properties induced by the interactions between these components in an integrative ensemble. 5,[11][12][13][14][15][16] Bimetallic nanostructures, coupling a surface plasmon resonance (SPR, Scheme S1 †) functionality with an efficient cocatalytic effect, could be an ideal candidate to simultaneously modulate the photoabsorption and steer the multichannel charge separation/transfer and reaction kinetics of semiconductors. [17][18][19][20][21] The design of effective bimetal-semiconductor composite photocatalysts requires the rational understanding of the structural design principle, because the randomly hybridizing counterparts would oen shield the SPR intensity and local electric eld of the plasmonic metal or weaken the net photoabsorption of the semiconductor.…”

Amine Functionalized Metal–Organic Framework Coordinated with Transition Metal Ions: d–d Transition Enhanced Optical Absorption and Role of Transition Metal Sites on Solar Light Driven H2 Production

“…However, the photocatalytic efficiency of MOFs is strongly affected due to their poor light‐harvesting and charge carrier separation ability . Various approaches have been reported to enhance the photocatalytic efficiency of MOFs by improving light‐harvesting and carrier separation capability . Especially, the optical properties of MOFs have been tuned by changing the organic linkers and metal nodes .…”