High-Density Ultrafine Au Nanocluster-Doped Co-LDH Nanocages for Enhanced Visible-Light-Driven CO₂ Reduction

Abstract

Developing effective photocatalysts for CO 2 reduction to high value-added chemicals or fuels is a promising strategy for alleviating serious environmental problems and energy crisis. Currently, the photocatalytic efficiency is still too slow to arouse industrial interest for most semiconductor photocatalysts due to their low CO 2 uptake, limited visible light capture capacity, and serious recombination of electron−hole. Herein, we successfully synthesized a high-density ultrafine Au cluster (∼0.7 nm)-doped cobalt-layered double hydroxide nanocage (Au/Co-LDH) photocatalyst through an in situ redox strategy to explore the structure−activity relationship in the CO 2 reduction system. A series of experimental characterizations showed that CO 2 adsorption, visible light capture capacity, and charge transfer rate are significantly enhanced due to the highly dispersed and ultrafine Au cluster doping. Density functional theory calculations indicate that Au doping also promoted charge redistribution at the active site, increased the density of states near the Fermi energy level, stabilized the *COOH intermediate, and reduced the energy barrier of the rate-determining step. As a result, Au/Co-LDH delivers a CO evolution rate of 5610 μmol g −1 h −1 toward CO 2 reduction under visible light (λ > 420 nm), which is 4 times and 22 times more active than the undoped one and Au nanoparticles, respectively. We believe that this work will provide an important implication for the development and optimization of photocatalysts for CO 2 reduction.

Synergistic Defect Sites and CoOx Nanoclusters in Polymeric Carbon Nitride for Enhanced Photocatalytic H2O2 Production

“…To evaluate the photon utilization efficiency in pure water, the apparent quantum yield (AQY) of CoO x -NvCN was measured. As shown in Figure c, the AQY of CoO x -NvCN decreased with the increase of wavelength, which was closely related to the trend of light absorption intensity, indicating that the obtained H 2 O 2 was indeed generated from the photon-induced catalytic reaction. , Significantly, CoO x -NvCN achieved an AQY of 5.73% under 420 nm monochromatic light irradiation (Table S9) while exhibiting a solar-to-chemical energy conversion (SCC) efficiency of 0.47% (Table S10), surpassing most recently reported CN-based photocatalysts in pure water. Table S11 comprehensively summarizes the performance comparison of CoO x -NvCN with recently reported advanced CN-based catalysts and other types of catalysts for H 2 O 2 generation.…”

Tandem Chemical Depolymerization and Photoreforming of Waste PET Plastic to High-Value-Added Chemicals

“…It can be observed that the light capture ability in the visible light region of Pt/g-C 3 N 4 is significantly enhanced due to the introduction of metal Pt nanoparticles, which will greatly improve the photocatalytic activity. The semicircular Nyquist plot of Pt/g-C 3 N 4 shows a smaller arc radius than that of pure g-C 3 N 4 (Figure b), indicating that Pt/g-C 3 N 4 has a better electronic conductivity and electron separation efficiency. − More intuitively, the peaks of Pt 4f shifted to lower binding energy under light compared to that in the dark (Figure c), which directly confirms the electron transfer from the support g-C 3 N 4 to metal Pt nanoparticles under light. Besides, the transfer process of photoinduced charge carriers on Pt/g-C 3 N 4 was identified by photoluminescence spectra (PL).…”

“…Besides, the transfer process of photoinduced charge carriers on Pt/g-C 3 N 4 was identified by photoluminescence spectra (PL). The PL intensity is positively correlated with the electron–hole recombination rate. − As shown in Figure d, an emission around 460 nm is observed for pure g-C 3 N 4 , Pt/g-C 3 N 4 , and Pt/Bulk g-C 3 N 4 samples. Compared with the pure g-C 3 N 4 and Pt/Bulk g-C 3 N 4 samples, the Pt/g-C 3 N 4 photocatalyst presented the lowest peak intensity, indicating the most efficient inhibition of charge carrier recombination due to the formation of heterojunctions between g-C 3 N 4 support and Pt nanoparticles, and the short path for photogenerated charge transfer in the small nanoscale carbon nitride nanospheres, which effectively facilitate the transfer and separation of the photogenerated electron–hole pairs at the interface.…”

Porphyrin-based metal–organic frameworks for photo(electro)catalytic CO2 reduction

“…), and noble metals (Ag nanoparticles (NPs), Au NPs, Pt NPs). 28,30 When sunlight irradiates the surface of the photocatalyst, the process of photocatalytic reaction occurs on the surface which is as follows: (1) CO 2 molecules are absorbed by the active sites of the photocatalyst; (2) light is harvested by the semiconductor photocatalyst; (3) light energy drives the separation of photogenerated carriers; (4) the photogenerated carriers migrate to the semiconductor's valence (VB) and conduction (CB) bands, respectively; (5) the photogenerated electrons in the CB undergo a reduction reaction with the adsorbed CO 2 ; and (6) product desorption from the photocatalyst surface takes place. This completes the entire catalytic reaction process.…”

“…16,17 Numerous reports have suggested various approaches to enhance the photocatalytic activity, which can be broadly categorized as structural engineering (doping elements, 18–20 defect engineering, 21–23 etc. ) and co-catalytic design (heterojunction, 24–27 loading noble metals, 28,29 single atom catalysis, 30,31 etc. ).…”