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Despite the direct utilizing metal‐organic frameworks (MOFs) as promising photocatalysts for H2O2 production, their activity and selectivity are still undesirable owing to the insufficient active centers, weak visible‐light absorption, and limited charge transfer. Herein, the Ce‐doped Ti‐based MOFs MIL‐125‐NH2 photocatalysts (Ce/TiMOFs) were synthesized by a facile impregnation‐coordination method, during which the doped Ce species could not only extend the visible‐light absorption edge but also provide new reactive sites for promoting the charge transfer and selectivity of two‐electron O2 reduction. Interestingly, the optimal Ce/TiMOFs‐0.010 achieved a rate of H2O2 yield of 2464 μM h−1 g−1 with ∼3.4‐fold improvement compared to TiMOFs, attributed to the faster conversion rate of the main reactive oxygen intermediates (⋅O2−) and improved average transfer electron number. This work provides an effective strategy to optimize the photocatalytic performances of MOFs and expands the application of MOFs in the sustainable energy production field. [ABSTRACT FROM AUTHOR]

Electrochemical nitrogen reduction reaction (NRR) under ambient conditions offers an environmentally benign and sustainable alternative for NH3 synthesis. Exploring highly active and robust NRR electrocatalysts is one of the prerequisites for developing sustainable N2/NH3 cycle systems. In this work, a surface chemistry rich TiO2/CeO2 frame is developed for electrochemical NRR, which is composed of ultrathin TiO2 nanosheets supported with CeO2 nanoparticles. Its unique porous framework as well as formed plentiful oxygen vacancies (OVs) and hetero‐interfaces collectively facilitate the adsorption/activation of N2 and transfer of electrons and protons. The catalyst can attain a high NH3 yield rate of 8.8 μg h−1 mg−1cat. and a Faradaic efficiency of 6.8 % at −0.25 V versus reversible hydrogen electrode, comparable with other reported Ti‐based and OVs‐contained catalysts. Moreover, the TiO2/CeO2 can maintain high durability over repeated 20 cycles. Therefore, this work heralds a new paradigm of fabricating framework‐structured catalyst with enriched hetero‐interfaces and defects toward effective and sustainable NH3 synthesis. [ABSTRACT FROM AUTHOR]

In this work, we have successfully triggered the aqueous auto‐redox reactions between reductive Ce(OH)3 and oxidative MnO4−/Pd2+ ions to form PdO/Mn3O4/CeO2 (PMC) nanocomposites. PMC could spontaneously self‐assemble into compact encapsulation on the surface of halloysite nanotubes (HNTs) to form the final one dimensional HNTs supported PMCs (HPMC). It is identified that there exists strong synergistic effects among the components of PdO, Mn3O4, and CeO2, and hence HPMC could show excellent performance on photoassisted thermal catalytic CH4 combustion that its light‐off temperature was sharply reduced to be 180 °C under visible light irradiation. Based on detailed studies, it is found that the catalytic reaction process well follows the classic MVK mechanism, and adsorption/activation of O2 into active oxygen species (O*) should be the rate‐determining step for CH4 conversion. [ABSTRACT FROM AUTHOR]

Inorganic nanomaterials have attracted much attention as enzyme mimics because of simple and stable spatial conformation of those artificially synthesized nanocatalysts. Cu2O, as an important kind of narrow band gap semiconductor, is identified as effective as visible‐light‐driven photocatalysts, which can catalyze decomposition of H2O2 into reactive oxygen species. Moreover, after forming CuxO/CeO2 hybrids, the strongly coupled interface between the two components will further improve their catalytic performance. In this paper, the authors try to construct FTO/TiO2/CuxO/CeO2 (1

The development of efficient catalysts is of great importance for hydrogen evolution reaction (HER) of water splitting via electrocatalytic/photocatalytic processes to remediate the current severe environmental and energy problems. By aid of the stabilization effects of uncoordinated groups and inherent pore‐confinement of amine‐functionalized metal–organic frameworks (NH2‐MIL‐125), two forms of Ru species including nanoparticles (NPs) and/or single atoms (SAs) can be firmly embedded in NH2‐MIL‐125 derived N‐doped TiO2/C support (N‐TC), and thus obtain two kinds of samples named Ru‐NPs/SAs@N‐TC and Ru‐SAs@N‐TC, respectively. In the synthetic process, the initial feeding amount of Ru3+ ions not only strongly determines the final size and dispersion states of Ru species but also the morphology and defective structures of N‐TC support. Impressively, Ru‐NPs/SAs@N‐TC exhibit superior catalytic activities to Ru‐SAs@N‐TC for either electrocatalytic or photocatalytic HER. This should be attributed to its larger specific surface area and benefiting from synergistic coupling of Ru NPs and Ru SAs. It is envisioned that the present work can provide a new avenue for development of high‐efficiency and multifunctional hybrid catalysts in sustainable energy conversion. [ABSTRACT FROM AUTHOR]

Development of novel methods to obtain highly active catalysts for photocatalytic hydrogen evolution is desired. This work reports a facile preannealing‐quenching strategy to synthesize oxygen vacancy‐rich anatase TiO2 hollow spheres. TiO2 hollow spheres are first synthesized via a versatile kinetics‐controlled coating method and then subjected to high temperature preannealing followed by rapid quenching in liquid‐nitrogen (−196 °C). The as‐quenched samples appear light grey suggesting the presence of abundant surface oxygen vacancies, which are subsequently confirmed by the comprehensive analyses of XRD, XPS and EPR spectra. The oxygen vacancies induced by quenching process are proved to have promoted the light adsorption and inhibited the recombination of photo‐induced charges for TiO2 hollow spheres, which obviously improve the photocatalytic performance of those samples. The results showed that the TiO2 hollow spheres quenched at 500 °C exhibited a robust stability and the most excellent photocatalytic performance for hydrogen evolution (413.5 μmol h−1) over other quenched samples and it displayed 1.51 times higher performance than that of samples normally cooled at 500 °C (273.7 μmol h−1). Herein, this liquid‐nitrogen quenching strategy presented here provides an effective route for the synthesis of high‐performance TiO2 for water splitting and have a promising prospect in the other application. It's a vacancy‐rich world! During the liquid‐nitrogen quenching process, the isolated O atoms on the TiO2 surface are partially frozen and lose the opportunity to return the crystallographic sites, leaving abundant oxygen vacancy on the surface. The oxygen vacancy‐rich TiO2 prepared via liquid‐nitrogen quenching exhibited outstanding advantages on photocatalytic H2 evolution. [ABSTRACT FROM AUTHOR]

In this work, we have successfully triggered the aqueous auto-redox reactions between reductive Ce(OH) 3 and oxidative MnO 4 - /Pd 2+ ions to form PdO/Mn 3 O 4 /CeO 2 (PMC) nanocomposites. PMC could spontaneously self-assemble into compact encapsulation on the surface of halloysite nanotubes (HNTs) to form the final one dimensional HNTs supported PMCs (HPMC). It is identified that there exists strong synergistic effects among the components of PdO, Mn 3 O 4 , and CeO 2 , and hence HPMC could show excellent performance on photoassisted thermal catalytic CH 4 combustion that its light-off temperature was sharply reduced to be 180 °C under visible light irradiation. Based on detailed studies, it is found that the catalytic reaction process well follows the classic MVK mechanism, and adsorption/activation of O 2 into active oxygen species (O*) should be the rate-determining step for CH 4 conversion., (© 2021 Wiley-VCH GmbH.)

Inorganic nanomaterials have attracted much attention as enzyme mimics because of simple and stable spatial conformation of those artificially synthesized nanocatalysts. Cu 2 O, as an important kind of narrow band gap semiconductor, is identified as effective as visible-light-driven photocatalysts, which can catalyze decomposition of H 2 O 2 into reactive oxygen species. Moreover, after forming Cu x O/CeO 2 hybrids, the strongly coupled interface between the two components will further improve their catalytic performance. In this paper, the authors try to construct FTO/TiO 2 /Cu x O/CeO 2 (1 < x < 2) nanohybrids with such a kind of active interface via a layer-by-layer electrodeposition strategy by aid of the following surface etching process. It is found that FTO/TiO 2 /Cu x O/CeO 2 exhibits good peroxidase mimic activity in the dark but much better performance under visible light irradiation (λ ≥ 420 nm) during catalytic oxidation of 3,3',5,5'-tetramethylbenzidine substrates in the presence of H 2 O 2 . Detailed characterizations disclose that the construction of TiO 2 /Cu 2 O pn-heterojunctions do effectively accelerate separation of photogenerated carriers, and the formation of a highly active Cu x O/CeO 2 interface is synergistically favorable for selectively generating singlet oxygen to boost the catalytic performance of FTO/TiO 2 /Cu x O/CeO 2 ., (© 2021 Wiley-VCH GmbH.)