Emerging Stacked Photocatalyst Design Enables Spatially Separated Ni(OH)₂ Redox Cocatalysts for Overall CO₂ Reduction and H₂O Oxidation

Abstract

Construction of photocatalytic systems with spatially separated dual cocatalysts is considered as a promising route to modulate charge separation/transfer, promote surface redox reactivities, and prevent unwanted reverse reactions. However, past efforts on the loading of spatially separated double‐cocatalysts are limited to hollow structured semiconductors with inner/outer surface and monocrystalline semiconductors with different exposed facets. To overcome this limitation, herein, enabled by a unique stacked photocatalyst design, a facile and versatile strategy for spatial separation of redox cocatalysts on various semiconductors without structural and morphological restriction is demonstrated. The smart design begins with the deposition of light‐harvesting semiconductors on reduced graphene oxide (rGO) nanosheets, followed with the coverage of Ni(OH)2 outer layer. The ternary photocatalysts exhibit superior activities and stabilities of H2O oxidation and selective CO2‐to‐CO reduction, remarkably surpassing other counterparts. The origin of the enhanced performance is attributed to the synergistic interplay of rGO@Ni(OH)2 reduction cocatalysts surrounding the semiconductors and Ni(OH)2 oxidation cocatalysts directly supported by the semiconductors, which mitigates the charge recombination, supplies highly active and selective sites for overall reactions, and preserves the semiconductors from photocorrosion. This work presents a new approach to regulating the position of dual cocatalysts and ameliorating the net efficiency of photoredox catalysis.

Stacking Engineering of Semiconductor Heterojunctions on Hollow Carbon Spheres for Boosting Photocatalytic CO2 Reduction

“…Such differentiated deposition sites of Pt and MnO x further confirm that the C/CdS@ZnIn 2 S 4 follows the Type-II charge transfer path rather than the direct Zscheme mechanism. 39 Taking the architecture of C/CdS@ZnIn 2 S 4 into consideration, a possible mechanism for the photocatalytic CO 2 reduction has been proposed. As illustrated in Figure 6e, the narrow-bandgap CdS core and the ZnIn 2 S 4 shell rather than the zero-bandgap carbon supporter are excited to generate photo-induced electrons and holes under visible light illumination.…”

Plasmonic Metal Mediated Charge Transfer in Stacked Core–Shell Semiconductor Heterojunction for Significantly Enhanced CO2 Photoreduction

“…Besides, as revealed by linear sweep voltammetry curves (Figure S17, Supporting Information), in contrast to Au loading, MoS 2 coating introduces more active sites for CO 2 reduction and H 2 O oxidation, benefiting the occurrence of overall redox reaction on the TiO 2 /Au@MoS 2 . [62,63] Previous researches have shown that MoS 2 is an efficient catalyst for O 2 evolution owing to its high hole mobility and powerful photo-oxidation ability. [64,65] When TiO 2 @MoS 2 /Au is taken into consideration, in addition to the sluggish consumption of electrons confined in TiO 2 core, the TiO 2 → MoS 2 hole migration and Au → MoS 2 hot electron injection accelerate the charge recombination in the MoS 2 interlayer (Figure S18, Supporting Information).…”

Spatially Separated Redox Cocatalysts on Ferroelectric Nanoplates for Improved Piezophotocatalytic CO2 Reduction and H2O Oxidation

“…Further H 2 18 O isotopic labeling experiment is also conducted, and the signal at m/z = 36 corresponding to 18 O 2 is detected by gas chromatography/mass spectrometry measurement, unequivocally verifying the fact that the evolved O 2 actually originates from H 2 O oxidation (Figure S8b). 55…”