The facile and scalable synthesis of manganese-doped nickel/nickel oxide heterostructures with high activity, outperforming the Pt benchmark, in neutral electrolytes.

To date there has been a lack of understanding on how photoexcited electron charge transfer can be beneficially combined in a hybrid photo-thermal-catalytic reaction. The effect of different excitation wavelengths on photo-thermal-catalytic oxidation by Au/TiO 2 and TiO 2 nanoparticles was studied via the gas-phase oxidation of ethanol over a temperature range of 100−250 °C under either visible light or UV illumination. Catalytic performance was assessed by monitoring the CO 2 yield. Despite being a weak thermal catalyst (5% catalytic enhancement in comparison to neat TiO 2 under thermal catalytic conditions), Au/TiO 2 displayed a considerable photo-thermal synergism in the photo-thermal regime (>175 °C), with over 50% and 100% increases in catalytic performance in comparison to neat TiO 2 under visible light and UV illumination, respectively. Photo-thermal-catalytic results and detailed probing of postreaction surface carbon species on Au/TiO 2 indicated that photo enhancement under UV illumination was due to congruent roles of the photo and thermal catalysis, while photo enhancement under visible light illumination was due to plasmonic-mediated electron charge transfer from the Au deposits to the TiO 2 support.

A stable and selective electrocatalyst for CO2 reduction was fabricated by covalently attaching graphitic carbon nitride onto multiwall carbon nanotubes (g-C3 N4 /MWCNTs). The as-prepared composite is able to reduce CO2 exclusively to CO with a maximum Faraday efficiency of 60 %, and no decay in the catalytic activity was observed even after 50 h of reaction. The enhanced catalytic activity towards CO2 reduction is attributed to the formation of active carbon-nitrogen bonds, high specific surface area, and improved material conductivity of the g-C3 N4 /MWCNT composite.

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Although photoexcitation has been employed to unlock the low-temperature equilibrium regimes of thermal catalysis, mechanism underlining potential interplay between electron excitations and surface chemical processes remains elusive. Here, we report an associative zinc oxide band-gap excitation and copper plasmonic excitation that can cooperatively promote methanol-production at the copper-zinc oxide interfacial perimeter of copper/zinc oxide/alumina (CZA) catalyst. Conversely, selective excitation of individual components only leads to the promotion of carbon monoxide production. Accompanied by the variation in surface copper oxidation state and local electronic structure of zinc, electrons originating from the zinc oxide excitation and copper plasmonic excitation serve to activate surface adsorbates, catalysing key elementary processes (namely formate conversion and hydrogen molecule activation), thus providing one explanation for the observed photothermal activity. These observations give valuable insights into the key elementary processes occurring on the surface of the CZA catalyst under light-heat dual activation.

Here, we demonstrate that structural defects can induce catalytic reactivity in simple metal oxides to deliver cost-effective alternatives to noble metal group catalysts. We detail a strategy for introducing multiple defect sites in a binary TiO2–SiO2 composite to invoke synergism for oxygen activation. Hydrogenation and UV light pretreatment were applied to generate two distinct and adjacent defect sites, Ti3+ and silica-based nonbridging oxygen hole centers (NBOHC)which work in unison to activate oxygen and oxidize formic acid under ambient conditions without light. The hydrogenation step was found to be crucial for rupturing Ti–O–Si bonds while first-principles calculations indicated that Si-doped TiO2 lowered the energy barrier for oxygen activation and formic acid dehydrogenation on the defect sites. Activity lost during the reaction was recoverable by catalyst reillumination. Defective metal oxides represent an appealing prospect in the pursuit of simple and readily accessible catalyst materials.

Research into photoenhanced heterogeneous catalysis with Au/TiO 2 has gained traction in recent years because of the potential for activity enhancement due to its localized surface plasmon resonance effects, including oxidation reactions. While others have observed and described the effects of C−C cleavage by Au/TiO 2 , how C−C cleavage occurs has not been reported to date. To elucidate the mechanism and to understand the fundamental impacts of visible and ultraviolet (UV) photoexcitation on the dynamics of gas phase ethanol oxidation, an in situ, quantitative diffuse reflectance infrared fourier transform spectroscopy analysis of the surface of Au/ TiO 2 and neat TiO 2 was performed. Key findings from the study include (i) discovery of exclusive oxalate species, a critical precursor to C−C cleavage, which is also an indicator of selective ethanol adsorption at the Au−TiO 2 interfacial perimeter, (ii) fortification of C−C bond cleavage by Au/TiO 2 via detection of single-carbon species such as formate and carbon monoxide on Au/TiO 2 in the dark under visible light illumination, (iii) validation of previous postulations regarding ethanol adsorption on TiO 2 followed by oxygen activation at the Au−TiO 2 interfacial perimeter, and (iv) in situ re-enactment of the different impacts by bandgap photoexcitation and plasmonically mediated charge transfer, under UV and visible light illumination, respectively, on ethanol oxidation by Au/TiO 2 and neat TiO 2 .