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As for the common synthesis methods of ameliorated Zn 2 SnO 4 (ZSO), additional oxides refer to Zn or Sn or Zn/Sn would be introduced into the doped system synchronously, thereby the achievement of doped pure ZSO appears particularly difficult. In this study, a novel bismuth (Bi) nanoparticles modified ZSO composite with oxygen vacancies (OVs-BZSO) was fabricated via a facile one-pot hydrothermal approach. According to XRD and XPS analysis results, it was found that the metallic Bi nanoparticles were successfully introduced into ZSO. In addition, based on the results of XPS and EPR measurements, the existence of OVs in the ZSO was also affirmed. On this basis, the DFT calculation was employed to reveal the position of OVs, the electronic structure and charge transport properties of the interface between Bi and ZSO. Furthermore, it was observed that the introduction of OVs not only diminishes the bandgap induced by an intermediate gap but also services as active centers to favor the adsorptions of small molecules such as NO, O 2 and H 2 O as revealed by DFT simulations to promote the formation of reactive species. While the addition of metallic Bi nanoparticles into ZSO for one thing enhances the light harvesting capacity endowed by SPR effect as evidenced by UV–vis DRS result, for another accelerates the separation of photo-generated carriers by virtue of Schottky barrier formed at the metallic Bi and ZSO interface. Therefore, the synergistic effect of OVs and Bi nanoparticles can thermodynamically drive the adsorption/activation of NO molecules, benefitting the directional migration and effective separation of electrons in OVs-BZSO, all of which serviced the efficient NO removal rate with the illumination of visible light. Meanwhile, for OVs-BZSO, in-situ infrared spectroscopy results indicated that the formation of toxic by-products was greatly bridled, thus a fresh charge transfer path: Bi nanoparticles → ZSO → gas molecules and a unique NO reaction path were proposed accordingly. This study can provide new insights on controllable preparation and reaction mechanism of ZSO-based photocatalysts. Zn 2 SnO 4 with the co-modification of metallic Bi nanoparticles and oxygen vacancies not only thermodynamically drives the adsorption/activation of molecules (NO, O 2 and H 2 O) but also alters the NO reaction path through greatly inhibiting the formation of toxic intermediates. ga1 • Metallic Bi modified Zn 2 SnO 4 with OVs was obtained by one-pot hydrothermal method. • The introduction of Bi/OVs sharply boosts the activity of Zn 2 SnO 4 for NO oxidation. • OVs as Lewis acid benefits the adsorption and activation of molecular NO. • Metallic Bi donors electrons to Zn 2 SnO 4 and improves the visible light harvesting. • The co-existence of Bi/OVs in Zn 2 SnO 4 inhibits the formation of toxic by-products. [ABSTRACT FROM AUTHOR]

• In-situ regulation of oxygen vacancies controlled by the crystal planes. • Oxygen vacancies promoted the valid separation of photogenerated electrons and holes. • Oxygen vacancies enhanced the adsorption and activation of O 2 and propane. • A multi-pathway enhancement mechanism in PTSCO was proposed. Crystallographic effects in photothermal synergistic catalytic oxidation (PTSCO) system for VOCs removal are essential but still lack in-depth systematic studies. Therefore, key factors and synergistic mechanism of propane removal by MnO 2 with different crystal planes in PTSCO system were investigated. The results showed that 160-M−300 with the mainly exposed (1 1 0) crystal plane displayed the optimal activity (T 90 = 235℃, TOF = 4.90 × 10-7·s−1) and long-term stability (40 h) due to the abundant oxygen vacancies (OVs) controlled by the crystal planes, outstanding low temperature reduction ability and higher oxygen mobility. OVs substantially enhanced the adsorption and activation of propane and O 2 , and accelerated the efficient separation of photogenerated electrons and holes by capturing the electrons. Correspondingly, density functional theory (DFT) calculations confirmed that (1 1 0) crystal facet had the lowest OVs generation energy and work function, based on which, a multi-pathway enhancement mechanism of PTSCO was proposed. This study clarified the crystal-PTSCO activity dependence, provided theoretical support for the efficient and energy-saving removal of low-carbon alkanes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dopant of Ag on MnCeO x promotes the catalytic activity for propane oxidation. • Ag dopant increases Mn4+ and Ce3+ concentrations. • Ag dopant enhances surface oxygen migration capability. • Ag dopant leads to a novel carboxylate formation path. The development of highly active catalysts for eliminating volatile organic compounds (VOCs) at low temperature is desirable but remains challenging. In this study, a series of Ag-loaded MnCeO x catalysts were fabricated. Catalysts with an Ag loading of 5 wt% exhibited the highest catalytic activity (T 90 = 242 °C) and excellent stability in H 2 O, NO 2 , and CO atmosphere. Characterization results revealed that the introduction of Ag increased Mn4+ and Ce3+ concentrations and enhanced surface oxygen migration capability, which is conducive to the adsorption and dissociation of propane and O 2. Combining in-situ diffuse reflectance infrared Fourier transform and discrete Fourier transform calculation revealed a novel propane oxidation pathway on MnCeO x and Ag/MnCeO x. The addition of Ag species can convert propane into propylene in the initial stage and reduce the activation energy. This study supplied a novel insight into Ag-doped catalysts catalytic mechanism for VOCs oxidation reaction. [ABSTRACT FROM AUTHOR]

A single-molecule confinement-sulfurization strategy was proposed to construct ultrafine Co-MoS 2 monolayer catalysts, employing oil-soluble POMs as precursors. Well-defined Co 2 Mo 10 -POMs were introduced for regulating CoMoS sites at atomic scale, exhibiting high intrinsic activities in VR HCK. [Display omitted] • Ultrafine Co-MoS 2 monolayer catalysts were controllably fabricated from the oil-soluble polyoxometalate (POM) precursors. • The POM anions were encapsulated and confined by organic surfactant cations at single-molecule level. • Well-defined Co 2 Mo 10 POMs were introduced for regulating CoMoS active sites at atomic scale. • CoMoS active sites show excellent catalytic performance for slurry phase hydrocracking of vacuum residue. • The structures and catalytic mechanisms of CoMoS sites were revealed by coupling XAFS with DFT calculations. Herein, a novel single-molecule confinement-sulfurization strategy was proposed to construct ultrafine Co-MoS 2 monolayer catalysts by using oil-soluble single-molecule polyoxometalates (POMs), (DODA) 6 Co 2 Mo 10 , as precursors. Well-defined Co 2 Mo 10 -POM, acting as molecular pre-assembling platform, is introduced for the atomically precise construction of bimetallic sites. Highly efficient conversion of VR under severe condition is realized with (DODA) 6 Co 2 Mo 10. The origin of prominent catalytic performance can be attributed to the in-situ formation of ultrafine single-layered Mo-based nanosheets with abundant exposed CoMoS active sites. By combining synchrotron radiation-based X-ray absorption spectroscopy and density functional theory calculations, we further discover that there is clearly intimate interaction between Mo and Co atoms and the dissociation of molecular hydrogen at CoMoS phases is energetically preferred, leading to remarkable hydrogenation and coke suppression activity. This work highlights an idea on the rational design and targeted synthesis of ultrafine bimetallic catalysts for slurry phase HCK with dramatically synergistic catalysis. [ABSTRACT FROM AUTHOR]

• C 3 N 4 with N3 C vacancy was obtained by calcination the mixture of azodicarbonamide and melamine. • The introduction of N3 C vacancy sharply improves the photoreactivity of C 3 N 4 for NO oxidation. • N3 C vacancy stimulates the adsorption of O 2 , boosting the production of singlet oxygen (1O 2). • Photo-oxiation of NO by produced 1O 2 sharply suppresses the formation of harmful NO 2. • A potential and sustainable route for the steady and efficient NO-oxidation was developed. The introduction of nitrogen vacancy to C 3 N 4 holds promise in the photocatalytic behavior improvement. Yet, minimal literatures on reaction and stability mechanisms are presently available in the NO-oxidation reaction of C 3 N 4. Here C 3 N 4 with three coordinated (N3 C) nitrogen vacancy was prepared by directly calcining the mixture of azodicarbonamide and melamine. Unlike previously reported C 3 N 4 that exhibits an obvious deactivation beyond 30 min (>10% loss of reactivity after one cycle) and high in-situ formed NO 2 concentration (>100 ppb), the C 3 N 4 with three coordinated (N3 C) nitrogen vacancy exerts increased NO-oxidation performance (40.3%, ~2.28 times higher than that of pristine C 3 N 4 with a NO-removal rate of 17.7%) and suppressed in-situ produced NO 2 (36.3 ppb, decreased by 76.6 ppb compared to pure C 3 N 4) as well excellent stability (<2% loss of activity after a 5 h cycling test). DFT calculations reveal that, intermediates (NO 2) and end-products (NO 2 – and NO 3 –) can weakly adsorp on the surface of C 3 N 4 with three coordinated (N3 C) nitrogen vacancy, thus rendering a well maintained activity. Based on the time-dependent ESR measurements, the 1O 2 generation, which achieving from the O 2 activation process, can compensate for the consumption of major reactive species and thus support the remarkable reusability. Therefore, this study provides a potential and sustainable route for the steady and efficient NO-oxidation. [ABSTRACT FROM AUTHOR]