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A newly developed diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS) cell for the in situ study of non-thermal plasma (NTP)-assisted heterogeneously catalysed reactions is presented and evaluated using methane oxidation over a Pd/Al 2 O 3 catalyst. By using the new fixed bed plasma DRIFTS cell coupled with mass spectrometry, the NTP discharge is generated inside the catalyst bed and allows simultaneous, in situ DRIFTS analysis to be undertaken. The spectroscopy has revealed that the formation of surface species, e.g. formate and carbonate, is significantly influenced by NTP generation under methane oxidation conditions at different voltages when comparing with the conventionally thermal activation. During the NTP-DRIFTS-MS measurements, it is also found that there is no signal interference between IR beam and plasma plume, making this a viable DRIFTS system for studying the plasma catalysis.

Three-coordinated framework Fe sites in zeolites were theoretically demonstrated to show Lewis acidity and superior catalytic activity for the titled reaction compared with extra-framework Fe sites that were generally considered as the active species, while the corresponding Al sites are not reactive. This catalytic distinctness is ascribed to their divergent α-oxygen structures.

The effects of HCl on the oxidation of CH 4 at CeO 2 (111) have been studied by using density functional theory calculations corrected by on-site Coulomb interactions (DFT+U). The calculated results show that the presence of HCl barely affects the CH 4 dissociation, but can provide new reaction channels to produce CH 3 Cl. The effects of surface defects and orientations on the surface reactivity were also considered. The total oxidation of CH 4 can be partially prohibited by the high barriers for the further dissociation of CH 3 at reduced surfaces due to the strong electronic repulsion of heavily accumulated localized electrons. CeO 2 (110) shows higher activity and selectivity for CH 3 Cl formation than CeO 2 (111), indicating that the morphologies of CeO 2 nanocatalysts would be key to the catalytic activities toward CH 4 activation.

The chemically exfoliated 2D-MoS 2 has a mixture of 1T (metallic) and 2H (semiconducting) phases. It has shown a considerably good catalytic activity for hydrogen evolution reaction (HER), proceeding via electrochemical as well as photochemical pathways. Experimentalists have utilized triethanolamine or other sacrificial donors along with Eosin Y as a photosensitizer. But the potential of this reaction has not yet been fully explored as the sacrificial donor is wasted in the oxidation process. The oxidation cycle of this process can be used in many organic transformation(s). Herein, we report the use of the oxidative cycle for efficient cross dehydrogenative coupling (CDC) reaction with tetrahydroisoquinoline and indole substrates as well as their derivatives, parallel to HER. The reaction results in good to excellent yield of the corresponding product under visible light irradiation at room temperature. The mechanistic investigation has also been carried out. This study is a potential example of how to fully harness the oxidation and reduction cycles of many semiconductor based photocatalysts.

This paper describes the development of quantitative structure–enantioselectivity and–activity relationships for the asymmetric hydroformylation of styrene by Rh– diphosphane . We used 3D steric- and electrostatic-type interaction fields derived from DFT calculations, and generated alignment-independent descriptors using GRid INdependent Descriptor (GRIND) methodology. The obtained QSPR models showed statistical significance and predictive ability. The most predictive model for enantioselectivity was obtained using steric-type 3D fields (MSF) based on the local curvature electron density isosurface that accounts for catalyst shape ( r 2 = 0.92, q 2 = 0.68). We obtained the most predictive model for activity using a combination of shape- and electrostatic-based 3D fields ( r 2 = 0.99, q 2 = 0.74). The use of chemically meaningful descriptors provides insight into the factors governing catalytic activity and selectivity. The worst predicted ligand , kelliphite, showed the lowest preference for equatorial–apical coordination and low selectivity, which suggests that its intrinsic enantiotopic differentiation capacity can be lost through the occurrence of bis-equatorial paths. The selective catalysts Rh–chiraphite, –binapine, –diazaphospholane, and –yanphos showed the same pattern as Rh–binaphos, for which the origin of stereoinduction is known: the chirality at the apical site discriminates one alkene coordination path and one enantiomer. Ligands with electron withdrawing groups at phosphorus atoms such as chiraphite, kelliphite, binaphos, and diazaphospholane reduce ligand basicity and promote catalytic activity effectively. However, more complex relationships underlie the origin of activity, and the shape of the catalyst also needs to be considered such as for the Ph-BPE ligand . Comparison with previous studies suggests that reduction of the steric hindrance at the reaction centre which favors alkene coordination and insertion would also promote catalytic activity.

Visible light photoredox catalysis is emerging as a versatile technique for a great variety of chemical transformations. Specifically, Ru(bpy) 3 2+ has been widely used as a transition metal-based photocatalyst; however, little if any attention has been paid to the thermodynamic analysis of the photoredox processes that occur in the photocatalytic cycle of the studied reactions or, even more interestingly, to the examination of the kinetic feasibility of the involved processes. In addition, only a few studies on the progress of the reaction have been performed. Organic halides constitute a major concern for environmental remediation since they are reluctant towards aerobic oxidation. Therefore, p -halonitrobenzene (X-NB) derivatives have been selected in the present work as the model compounds to obtain a deeper understanding of their photocatalytic reduction using visible light and Ru(bpy) 3 2+ . Thermodynamic estimations were made on the basis of the experimentally determined energy of the LUMO of Ru(bpy) 3 2+ , which was determined to be 54.5 kcal mol ?1 from the cross-point of the normalized emission and excitation spectra, and redox potentials of X-NB and several sacrificial amines. As anticipated from chemical intuition, the feasibility of the global photoredox process increased upon going down in the group of halogens regardless of the participation of the oxidative or reductive quenching cycles. To unequivocally demonstrate the direct participation of the excited state of Ru(bpy) 3 2+ in the photoreduction, steady-state and time-resolved experiments were carried out upon increasing X-NB or amine concentration; this allowed determining the quenching rate constants for the electron transfer processes, which were found to be in the range of 10 8 M ?1 s ?1 for the X-NB and 10 6 M ?1 s ?1 for the amines. Therefore, the main role of the oxidative quenching cycle has been demonstrated under the experimental conditions employed. A good correlation was found between the thermodynamic and kinetic parameters, in agreement with the expectations from Marcus theory. Upon optimization of the reaction conditions, reductive dehalogenation was found to occur leading to the parent nitrobenzene.

Hydrosilylation of aldehydes and ketones catalysed by nickel acetate and tricyclohexylphosphine as the catalytic system was demonstrated using polymethylhydrosiloxane as a cheap reducing reagent.

A dye-like azo-carboxylic acid was chosen as an organic linker to construct a Gd 3+ based metal–organic framework: [Gd 2 (abtc)(H 2 O) 2 (OH) 2 ]·2H 2 O (Gd-MOF) (H 4 abtc = 3,3′,5,5′-azobenzene tetracarboxylic acid). The ultra-stable Gd-MOF possesses a HOMO–LUMO gap of 2.35 eV determined by UV-vis spectroscopy with an absorption edge at 530 nm, which presents effective photocatalytic activity for hydrogen evolution under UV-vis light illumination due to the porous structure and excellent light absorption of the dye-like ligand. To further enhance the photocatalytic activity, different amounts of Ag (1.0–2.0%) were deposited on Gd-MOF as a co-catalyst. The results of electrochemical impedance spectroscopy (EIS) and photoluminescence spectroscopy (PL) clearly indicate that the reaction proceeds through the electron transfer from Gd-MOF to the deposited Ag. Especially, Ag(1.5)/Gd-MOF exhibits significant improvement in the hydrogen evolution rate, which is about 1.5 times greater compared to that of bare Gd-MOF.

In order to solve the increasingly serious environmental pollution and energy crisis as soon as possible, engineering of two-dimensional/two-dimensional (2D/2D) S-scheme heterojunctions is in the spotlight. Herein, two-dimensional/two-dimensional (2D/2D) S-scheme Fe 2 O 3 /Bi 2 MoO 6 was designed and fabricated through a facile hydrothermal strategy, which constructed an advanced photocatalytic-Fenton coupling system. With the assistance of a low concentration of H 2 O 2 , the 2D/2D Fe 2 O 3 /Bi 2 MoO 6 with an Fe 2 O 3 weight ratio of 0.5% displayed significantly enhanced photo-Fenton catalytic activity toward tetracycline, which was 3.2 and 2.0 times that of Fe 2 O 3 and Bi 2 MoO 6 , respectively. The markedly enhanced photo-Fenton catalytic activity was attributed to the large surface area and efficient charge transfer of 2D/2D S-scheme Fe 2 O 3 /Bi 2 MoO 6 , as well as the photo-Fenton system constructed by H 2 O 2 and continuous Fe 3+ /Fe 2+ conversion under visible light irradiation. According to the active species trapping experiments and photoluminescence spectra, a novel 2D/2D S-scheme charge transfer mechanism of Fe 2 O 3 /Bi 2 MoO 6 was reasonably proposed. Fe 2 O 3 /Bi 2 MoO 6 composites displayed a broad application prospect due to their recyclability demonstrated by the cycling experiments. This work provides strong evidence that 2D/2D S-scheme Fe 2 O 3 /Bi 2 MoO 6 heterostructures are promising candidates for the photo-Fenton treatment of antibiotics.

Highly dispersed Ag–Pd alloys deposited on an amine-functionalized UiO-66(NH 2 –UiO-66) have been successfully prepared via a pre-coordination method. The as-synthesized AgPd@NH 2 –UiO-66 catalyst exhibited 100% H 2 selectivity and a high catalytic activity (TOF = 103 h ?1 ) toward the dehydrogenation of formic acid at room temperature without any additives, which is among the highest values ever reported. Our study further reveals that the synergetic effect between the Ag–Pd alloy and NH 2 –UiO-66 support play a key role for the efficient catalytic dehydrogenation of formic acid.