Photo-mediated co-loading of highly dispersed MnOx-Pt on g-C3N4 boosts the ambient catalytic oxidation of formaldehyde

Synergically regulated silver species and surface oxygen on manganese oxide for promoted activity of formaldehyde oxidation

Formaldehyde (HCHO) is a common indoor pollutant that is detrimental to human health. Its efficient removal has become an urgent demand to reduce the public health risk. In this work, Ag-MnOx-based catalysts were prepared and activated under different atmosphere (i.e., air, hydrogen (H2) and carbon monoxide (CO)) for efficient oxidation of HCHO. The catalyst activated with CO (Ag/Mn-CO) displayed the highest activity among the tested samples with 90% conversion at 100°C under a gas space velocity of 75,000 mL/(gcat·hr). Complementary characterizations demonstrate that CO reduction treatment resulted in synergically regulated content of surface oxygen on support to adsorb/activate HCHO and size of Ag particle to dissociate oxygen to oxidize the adsorbed HCHO. In contrast, other catalysts lack for either abundant surface oxygen species or metallic silver with the appropriate particle size, so that the integrate activity is limited by one specific reaction step. This study contributes to elucidating the mechanisms regulating the oxidation activity of Ag-based catalysts.

Advances in photochemical deposition for controllable synthesis of heterogeneous catalysts

Photochemical deposition has been attracting increasing attention for preparing nano-catalysts due to its mild reaction conditions, simplicity, green and safe characteristics, and potential for various applications in photocatalysis, thermal catalysis, and electrocatalysis. In this review, we provide an overview of recent advances in photochemical deposition methods for fabricating heterogeneous catalysts, and summarize the factors that influence the nucleation and growth of metal nanoparticles during the photochemical process. Specifically, we focus on the various factors including surface defects, crystal facets, surface properties and the surface plasmon effect on the size, morphology and distribution control of metal and metal oxide nanoparticles on semiconductors. The control of the photogenerated charges and the triggered photochemical reactions have been proved to be significant in the photochemical deposition process. Besides, the applications of the obtained catalytic materials in thermal catalysis and electrocatalysis is highlighted, considering that many reviews have covered photocatalysis applications. We first introduce the principle of photodeposition, nucleation and growth theory, and factors affecting photodeposition. Then, we introduce photodeposition methods that can achieve "controlled" photodeposition from a strategic perspective. Finally, we summarize the fruitful results of controlled photodeposition and provide future prospects for the development of controlled photodeposition technologies and methods, as well as the deepening and expansion of applications.

Photo-assisted sequential assembling of uniform metal nanoclusters on semiconductor support

Dispersing metal nanoclusters on the oxide supports is attracting close attention in heterogeneous catalysis, but great challenges still lie in controlling the size and dispersion of nanoclusters due to the inevitable agglomeration. Here, we propose a sequential photochemical deposition strategy named “first store, and then release” to uniformly fabricate the size-controlling noble metal nanoclusters on semiconductor oxides. Using the typical semiconductor TiO₂, the photoexcited electrons can be first stored as reduced species (e.g. Ti³⁺) under irradiation and the Ti³⁺ species can optimize both the nucleation and growth processes in dark reaction, resulting in a uniform dispersing of various noble metals (Au, Pt, Ag etc.) with size diameters of ∼1 nm. The nanoclusters catalysts exhibited superior performance in catalytic oxidation of HCHO compared with that of nanoparticles. This work brings a new and useful strategy to construct size-controlling noble metals on the oxide supports for heterogeneous catalysis and the related fields.

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Metal nanoclusters were deposited on semiconductors via sequential photodeposition

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Ti³⁺ species store the photoelectrons and optimize the nucleation and growth processes

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The catalysts exhibit superior performance in catalytic oxidation of HCHO

Enhanced HClO production from chloride by dual cocatalyst loaded WO3 under visible light

Photocatalytic production of HClO was improved more than twice by co-loading of Mn compared to the standard Pt/WO3.

Fabrication of g-C3N4 Nanosheets Anchored With Controllable CdS Nanoparticles for Enhanced Visible-Light Photocatalytic Performance

Herein, g-C₃N₄/CdS hybrids with controllable CdS nanoparticles anchoring on g-C₃N₄ nanosheets were constructed. The effects of CdS nanoparticles on photocatalytic H₂ production and organic molecule degradation for g-C₃N₄/CdS hybrids were investigated. The maximum rate of H₂ production for g-C₃N₄/CdS sample was 1,070.9 μmol g⁻¹ h⁻¹, which was about four times higher than that of the individual g-C₃N₄ nanosheet sample. The enhanced photocatalytic performance for prepared hybrids could be mainly attributed to the following causes: the formed heterojunctions can contribute to the light absorption and separation of photogenerated electrons and holes, the two-dimensional layered structure facilitates the transmission and transfer of electrons, and high specific surface area could provide more exposed active sites.

Irradiation regulates the size of Pt nanoparticles on Au@MnO2 nanosheets for electrocatalytic hydrogen evolution

The photoinduced LSPR effect of Au NPs was applied to load and adjust the size of precious metal (Pt and Ag) NPs on MnO2 nanosheets.

In Situ Photodeposited Construction of Pt-CdS/g-C3N4-MnOx Composite Photocatalyst for Efficient Visible-Light-Driven Overall Water Splitting

For converting the renewable solar energy to hydrogen (H₂) energy by photocatalytic (PC) overall water splitting (OWS), visible-light-driven photocatalysts are especially desired. Herein, a model CdS/g-C₃N₄ photocatalyst with a type II heterojunction is first demonstrated via a facile coupling of g-C₃N₄ nanosheets and CdS nanorods. After being combined with in situ photodeposited 3 wt % Pt and 4 wt % MnO_x dual cocatalysts simultaneously, the optimal visible-light-driven (λ > 400 nm) composite photocatalyst of Pt-CdS/g-C₃N₄-MnO_x gives a H₂ generation rate of 9.244 μmol h^-1 (924.4 μmol h^-1 g^-1) and a O₂ evolution rate of 4.6 μmol h^-1 (460 μmol h^-1 g^-1) in pure water, which is over 420 times higher than that of pure CdS nanorods loaded with 0.5 wt % Pt. The apparent quantum efficiency (AQE) reaches about 3.389% (at 400 nm) and 1.745% (at 420 nm), respectively. The combination of a type II heterojunction and simultaneous in situ photodeposition of the dual cocatalysts results in a dramatically improved PC efficiency and a long-term stability of the CdS/g-C₃N₄ visible-light-driven photocatalyst for OWS.