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Mn3O4 nanoparticles encapsulated inside carbon nanospheres supported on a carbon plate (Mn3O4@CS/CP) were designed, their bifunctional electrocatalytic performance for both, the oxygen evolution reaction (OER) at the anode and the oxygen reduction reaction (ORR) at the cathode were studied in alkaline solution. The prepared Mn3O4@CS/CP catalyst exhibits excellent electrocatalytic performance towards ORR, with less negative onset potential and long durability. Combining the results of in‐situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations, it is revealed that Mn3O4 acts as active site for ORR to promote the transformation of OH* into OH−. In addition, Mn3O4@CS/CP possesses an excellent electrochemical OER performances with the lower overpotential along with prosper Tafel slope and robust durability. DFT calculations show the transformation from O* to OOH* is the rate determining step for OER, and Mn3O4@CS/CP shows the minimum barrier, indicating that graphene sheet on the outer of Mn3O4 improves the transformation from O* to OOH*. The oxygen electrode activity parameter (potential difference between OER at current density of 10 mA/cm2 and ORR at current density of −2 mA/cm2) on Mn3O4@CS/CP is 0.72 V, which is superior to those of most bifunctional electrocatalysts reported to date, predicting a promising application in metal‐air batteries and fuel cells. Mn3O4 nanoparticles encapsulated inside carbon nanospheres supported on a carbon plate (Mn3O4@CS/CP) are designed, which exhibit exceptionally good stability and reversibility for ORR and OER. Furthermore, the electrocatalytic mechanism is analyzed. [ABSTRACT FROM AUTHOR]

Carbon composite fibers with Fe3O4, Fe3C, and TiO2 nanoparticles (Fe3O4/Fe3C/TiO2/C) were successfully fabricated using a facile dry-spinning approach, followed by annealing under argon flux. When used as the anode material of a lithium-ion battery, the Fe3O4/Fe3C/TiO2/C composite fibers achieved a reversible capacity of 702.1 mA h g−1 after 400 cycles at a current density of 100 mA g−1 and ca. 200 mA h g−1 at a current density of 1000 mA g−1 in 350 cycles. The superior cycling performance and high rate capability were attributed to the high theoretical specific capacity of Fe3O4, the catalytic activity of Fe3C, the structural stability of TiO2, and the buffer function of carbon fiber. Compared with the corresponding Fe3O4/Fe3C/C and TiO2/C composite fibers, the Fe3O4/Fe3C/TiO2/C product exhibited higher cycling and rate performances due to the synergetic effect among the Fe3O4, Fe3C, TiO2 and carbon components. [ABSTRACT FROM AUTHOR]

Platinum nanocubes, surfactant free, colloidal platinum, halides, electrochemistry Cover Feature: Controllable Surfactant-free Synthesis of Colloidal Platinum Nanocuboids Enabled by Bromide Ions and Carbon Monoxide (ChemElectroChem 11/2022) Keywords: platinum nanocubes; surfactant free; colloidal platinum; halides; electrochemistry EN platinum nanocubes surfactant free colloidal platinum halides electrochemistry 1 1 1 07/04/22 20220627 NES 220627 B The Cover Feature b shows a 3D view image of Pt nanocube and nanobar and emphasizes the critical roles of carbon monoxide and bromide ions in forming platinum nanomaterials in the ethylene glycol solvent. [Extracted from the article]

Organic pollutants have become an urgent problem for human health and the ecological system. The development of a multifunctional and efficient catalyst is of great significance for environmental governance. However, the catalytic conversion process of organic pollutants requires a large amount of energy, and traditional energy supply may further exacerbate environmental pollution. Herein, we propose an integrated magnetic material system that can serve as a magnetic heating medium to provide energy and as catalyst to promote the catalytic reaction. Iron-encapsulated carbon nanotubes activate peroxomonosulfate to generate active free radicals, achieving nearly complete degradation of the organic pollutant Orange II. The reaction exhibits excellent stability and repeatability, which may be attributed to the heating method applied to the magnetic sites, allowing the iron-encapsulated carbon nanotubes to maintain a stable structure. Further loading with Ag allows the catalyst to achieve near 100 % conversion of formaldehyde in air. This study aims to provide an effective and green strategy for environmental pollution treatment by integrating magnetic induction heating and catalytic conversion technology. [Display omitted] • Fe@NCNTs serve as an induction heating medium and catalyst for advanced oxidation. • Fe@NCNTs generate induction heat with high effective specific absorption rate. • Fe@NCNTs activate peroxomonosulfate to generate active free radicals. • The integrated system achieves complete degradation of Orange II in water and formaldehyde in air. [ABSTRACT FROM AUTHOR]

The difference of peroxide decomposition on carbon nitrides (CNx) supported the transition-metal oxide catalysts is the key to EB oxidation activity and product selectivity. [Display omitted] • Ethylbenzene (EB) oxidation catalyzed by transition-metal oxides catalysts is performed. • Co 3 O 4 /CN x displays the highest activity and considerable acetophenone(AcPO) selectivity. • CuO/CN x shows the moderate activity and highest AcPO selectivity. • The difference of peroxide decomposition on catalyst is the key to EB oxidation activity and product selectivity. Selective oxidation of aromatics via a free-radical process is a crucial ingredient in the chemical industry, in which the transformation of hydroperoxide was considered the key step to facilitate the reaction. In this study, the aerobic oxidation of ethylbenzene (EB) to acetophenone (AcPO) catalyzed by carbon nitrides (CN x) supported the transition-metal oxides was performed. Among these catalysts, Co 3 O 4 /CN x displayed the highest activity with 48.09 % EB conversion and 77.8 % AcPO selectivity, due to the efficient decomposition of 1-phenylethyl hydroperoxide (PEHP). Notably, in the case of CuO/CN x , the relatively low EB conversion (19.8 %) and high selectivity of AcPO (70.2 %) were observed, while almost no PEHP was detected. Further mechanism investigations revealed that the decomposition of hydroperoxide over CuO/CN x was too fast to generate the reactive free-radicals, which could not efficiently facilitate the propagation steps. Moreover, the addition of tert -butyl hydroperoxide (TBHP) participated in the α-H abstraction of EB and facilitated of radical propagation, showing the distinguished activities over Co 3 O 4 /CN x and CuO/CN x. [ABSTRACT FROM AUTHOR]

[Display omitted] • A mathematical model of the process of CO electrooxidation is established. • The surface sites are categorized into active and nonactive ones. • A certain ratio of nonactive sites should be kept for obtaining higher current density. • Balancing the micro-kinetics and mass transport rates is essential. • Nonactive sites are the reservoir of *CO for surface oxidation. The distribution and type of exposed surface sites are essential aspects of kinetics which should be considered together with mass transport in an electrochemical process, since multiple types of functional sites may coexist on electrocatalyst surfaces. In this study, we categorize the surface sites into active sites where the dissociation of water molecule and CO oxidation take place and nonactive sites where CO is adsorbed. By solving the bulk diffusion, adsorption, surface diffusion and reaction using the Fick's diffusion law, reaction rate law, and Butler-Volmer equation, it is shown that the catalysts surface with a certain ratio of nonactive sites possesses high current rather than only with a type of active sites. More importantly, the high steady-state current can be obtained by balancing the micro-kinetics and mass transport. The findings provide a new strategy of catalyst design and electrochemical operation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mesoporous carbon monolith (MCM) was prepared via a polymerization-pyrolysis method. • A self-designed device for the removal of pollutants with the aid of an electric field was developed. • The high removal efficiency for the removal of orgainic and inorganic pollutants were observed. • High regeneration of MCM was observed through the efficient electro-desorption process. • A concentration of 36.23 mg L-1 Cu2+ after 10 cycles enrichments was obtained. Electro-adsorption is considered an attractive and efficient technology for wastewater treatment, which still faces challenges for practical applications. Mesoporous carbon monolith (MCM) as an adsorbent with the aid of an electric field in a self-designed device via a flow-through model was developed. The high removal performances for organic (242.72 and 195.31 mg g−1 for methylene blue and ofloxacin, respectively) and inorganic (33.34 mg g−1 for Cu2+) contaminants with the aid of an electric field were obtained, higher than those without an electric field. The low resistance, high specific capacitance, and specific surface area of MCM were found to be beneficial for the transportation and storage of contaminants, thus improving the removal performance. The high recyclability of MCM with eight runs was also observed through the efficient electro-desorption process, which was helpful for the in-situ regeneration of the carbon adsorbent. Furthermore, the efficient electro-desorption of Cu2+ ions from the MCM surface could enrich Cu2+ in the defined solution with a concentration of 36.23 mg L-1 after ten times electro-adsorption/desorption recycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile method was established to evaluate the ET reaction rate. • Quantification of ET on d -CNTs is achieved. • Surface defects on d -CNTs are beneficial for the ET reaction rate. • ET ability of d -CNTs on MSI is revealed in the electrooxidation of glycerol. It is still an ongoing challenge to quantitatively determine the number of transferred electrons from carbon supports to metallic catalysts, which is highly related to their catalytic performance. In this work, a facile method combining electrochemical and spectroscopic technologies was proposed to evaluate the electron transfer (ET) reaction rate on carbon nanotubes (CNTs) with defects. Using 7,7,8,8-tetracyanoquinonedimethane (TCNQ) as an electron-accepting molecule, the transferred electrons from CNTs were quantitatively determined through the Beer-Lambert law and coulometric analysis. It was revealed that the edge defects on CNTs are beneficial for the ET reaction rate, due to the lower local work function. Hence, the defective CNTs supported Pt nanoparticles (Pt/ d -CNTs) performed the higher activity in the electrooxidation of glycerol, suggesting the influence of the ET ability of d -CNTs on the electronic metal-support interaction. This scenario is supported by density function theory calculation and X-ray photoelectron spectroscopy. Our results pave a new way to the facile evaluation of electronic metal–carbon interaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO 2 /CNTs catalysts for cumene oxidation is prepared. • Synergistic effect between MnO 2 and CNTs facilitating CHP decomposition is observed. • Kinetic modelling of 7 elementary steps is established. • MnO 2 /CNTs mainly accelerates the initial and terminal steps. • Enhanced k 80 and reduced E a are obtained over MnO 2 /CNTs. Synergistic effects between the carbon materials and metal oxides usually are considered as the significant factor in the selective oxidation of hydrocarbons. In current study, MnO 2 /CNTs catalysts were prepared under mild condition and applied in the cumene oxidation. As high as 73.44% cumene conversion with 59.06% selectivity of 2-phenyl-2-propanol(PP) was obtained over 21.23-MnO 2 /CNTs, which is much higher than those of CNTs-catalysis and MnO 2 -catalysis systems. The decomposition of cumene hydroperoxide (CHP), a key step for cumene oxidation, was proved to be facilitated by the interaction between MnO 2 nanoparticles and CNTs, which also confirmed from the DFT calculations. These results demonstrated that the synergistic effect between MnO 2 nanoparticles and CNTs would greatly enhance the activity and tune the distribution of products selectivity. The kinetic modeling study in this work further revealed that the interactions between MnO 2 nanoparticles and CNTs would accelerate all the elementary steps, especially, the homolytic cleavage of CHP. The reaction rate constant (k 80 = 9 h−1) for 21.23-MnO 2 /CNTs is 450-folds of CNTs (k 80 = 0.02 h−1). Moreover, the concentration distributions of acetophenone (AP) and PP were well illustrated from the kinetic study. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single/dual-elemental doped CNTs were obtained assisted by defluorination of FCNTs. • Electronic metal–carbon interaction can be regulated by heteroatom doping CNTs. • The binding energies of Pd can be as a descriptor for phenol hydrogenation. Heteroatom doped carbon materials have been synthesized and served as catalyst supports for Pd nanoparticles (NPs). Numerous Pd-carbon catalysts can be produced via single-, dual-, and multi-doping heteroatoms into carbon supports. Therefore, it is highly desired to seek a universal descriptor, regardless of the doping types, in guiding to the design of efficient catalysts. The electronic state of Pd affected by carbon supports is crucial in catalysis, which can be described by the binding energy (BE) accurately and conveniently using X-ray photon spectroscopy. In this work, the single (dual)-doped carbon nanotubes (CNTs) with tunable doping degrees were synthesized via thermal pyrolysis of heteroatom-containing precursors, accompanied by the defluorination of fluorinated CNTs. Density functional theory results show that the charge distributions of the doped-CNTs are determined by the doping configurations. After loading Pd NPs, the charge of the support redistributes. Meanwhile, the BEs of Pd0 3d5/2 change correspondingly due to the electronic metal–carbon interaction (EMCI). Eventually, Pd NPs with different electronic states show the difference in the turnover frequency of phenol hydrogenation. Therefore, the electronic state of Pd NPs can be considered as a proper descriptor for estimating the catalytic performance and indicator for developing highly efficient catalysts. [ABSTRACT FROM AUTHOR]

MXenes, 2D transition metal carbides/nitrides, have been demonstrated as promising platform for fabricating novel composites with interesting photo-/electrochemical properties. It is desirable to gain insights into the reactivity of MXenes, enabling the controllable transformation of MXenes. Here, a one-pot hydrothermal synthesis method of MXene-based photocatalyst is validated by harnessing the reducibility of Nb 2 CT x MXene. The origin of reducibility of Nb 2 CT x during the hydrothermal oxidation process was demonstrated as the active hydrogen produced from the water splitting in the presence of Nb 2 CT x , which reduced Ru3+ in situ to Ru nanoparticles on Nb 2 O 5 nanowires derived from Nb 2 CT x. Compared with the traditional photo-deposition method, the chemical valance of the noble metal Ru/Pt obtained by the one-pot synthesis method was closer to the metal state, which reduced the charge transfer resistance by 82.5%. It led to the photocatalytic hydrogen production of 10.11 mmol·h−1·g−1 with 41.25% apparent quantum yield at 313 nm. [Display omitted] • Harnessing hydrothermal reactions over Nb 2 C allows for a one-pot synthesis of Ru/Nb 2 O 5 @Nb 2 C. • Hydrogen released from water is the origin of reducibility of MXene. • One-pot synthesis reduces the carrier transfer resistance by 82.5% compared to photo-deposition. • Ru/Nb 2 O 5 @Nb 2 C achieves a quantum efficiency of 41.25% for water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1D Nb 2 O 5 nanorod arrays were grown in-situ on 2D Nb 2 CT x MXenes. • Ag nanoparticles were photodeposited on the Nb 2 O 5 nanorods to form 0D/1D/2D hybrids. • OH predominantly adsorbed on Nb 2 CT x resulted in a low work function of 2.7 eV. • The holes and electrons were separated by Nb 2 CT x and Ag, respectively. • Ag/Nb 2 O 5 @Nb 2 CT x reached a record HER activity among the niobium-based photocatalysts. Steering charge kinetics is one of the most urgent unsolved issues in photocatalysis. The effective spatial separation of photogenerated electron-hole pairs is particularly important in the design and controllable preparation of nano-photocatalysts. Herein, one-dimensional Nb 2 O 5 nanorod arrays with [0 0 1] orientation were grown in-situ on two-dimensional Nb 2 CT x MXenes through a facile hydrothermal method for the first time. Ag nanoparticles were then photodeposited on the Nb 2 O 5 nanorods to form hierarchical 0D/1D/2D nanohybrids. It was experimentally demonstrated that OH is predominantly adsorbed on Nb 2 CT x as termination groups, which resulted in a low work function (2.7 eV). Thanks to the unique structure, the highly active [0 0 1] Nb 2 O 5 nanorods afford high-efficiency photogeneration of electron-hole pairs, while the low-work-function OH terminated Nb 2 CT x allows for trapping holes, and Ag nanoparticles act as electron reservoir and sites of hydrogen evolution reaction (HER). The ternary Ag/Nb 2 O 5 @Nb 2 CT x nanohybrids reached a record HER activity (682.2 and 824.2 μmol·g-1h−1 use methanol and glycerol as sacrificial agents, respectively) among the niobium-based photocatalysts, demonstrating the potential of MXenes as a platform for the synthesis of high-performance heterojunction structures, where the tunable electronic property is a key factor. [ABSTRACT FROM AUTHOR]

[Display omitted] • 98.5% hydrogen is produced from sorption-enhanced steam reforming of iso -octane. • 90% hydrogen yield was achieved for 10 SESRI-decarbonation cycles. • The SESRI reaction lowered the reaction temperature by >200 °C. Liquid hydrocarbon fuels produced from fossil resources are potential portable hydrogen carriers given their sufficient supply and extensively available infrastructures. However, effective approaches to hydrogen production from liquid hydrocarbons fuels are still insufficient, especially in the context of carbon emission control. Here, we report that high-purity hydrogen is produced with minimized CO 2 emissions via the sorption enhanced steam reforming of iso -octane (SESRI), a model compound of gasoline. With a Pd-promoted Ni-CaO-Ca 12 Al 14 O 33 bi-functional catalyst, 98.0% purity of hydrogen with 90% hydrogen yield was obtained for 10 consecutive SESRI-decarbonation cycles. XRD, SEM, and TEM techniques revealed that structural and morphological properties of the bi-functional catalyst were preserved after 10 cycles. Raman spectroscopy, CO 2 -TPO and TGA further demonstrated that coke formation was substantially suppressed in the presence of Pd, which played a key role in maintaining stable SESRI performance in terms of hydrogen production. Our results provide a feasible alternative for production of high-purity hydrogen from liquid fossil fuels, thereby being prospective in meeting the demand of portable hydrogen on short to medium term basis. [ABSTRACT FROM AUTHOR]

Formaldehyde (HCHO) is harmful to environment and human health, even at extremely low concentrations. Catalytic oxidation on metal oxides is an effective method for HCHO removal. Transition metal oxides have attracted much attention due to its advantages of low cost and good redox properties, but it requires the high reaction temperature and energy consumption to reach the good catalytic activity for HCHO removal. In this work, Mn-Co mixed oxides supported on carbon nanotubes (CNTs) were prepared for enhancing the low-temperature catalytic activity of HCHO removal. The results of XRD, TEM and XPS characterization confirmed the formation of CoMn 2 O 4 solid solution on CNTs. The highest relative content of Co3+, Mn3+ and active lattice oxygen were achieved at the optimal composition of 3Mn-1Co. The HCHO oxidation test showed that CoMn 2 O 4 /CNTs (3Mn-1Co) had the best catalytic activity at 160 °C, obtaining 95% HCHO (100 ppm) removal efficiency and 95% CO 2 selectivity at GHSV = 30,000 mL g cat -1 h-1. Compared with the similar catalysts previously reported in literatures, CoMn 2 O 4 /CNTs was of the lower T 90 value for HCHO oxidation. Image 1 • Mn/Co molar ratio of 3:1 was prone to form CoMn 2 O 4 solid solution on CNTs. • The formation of active lattice oxygen on CoMn 2 O 4 was beneficial to HCHO oxidation. • The combination of CNTs and Co-Mn oxides solid solution is promising to prepare catalysts for HCHO removal. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal carbides/nitrides (MXenes) have shown great promise in various applications. However, mass production of MXenes suffers from the excessive use of toxic fluorine-containing reagents. Herein, a new method was validated for synthesizing MXenes from five MAX ceramics. The method features a minimized (stoichiometric) dosage of F-containing reagent (NaBF 4 ) and polyols (glycerol, erythritol, and xylitol) as the reaction solvent. Due to the sweetness of polyols and the low environmental impact, we refer to this method as a "sweet" synthesis of MXenes. An in-depth molecular dynamics simulation study, combined with experimental kinetic parameters, further revealed that the diffusion of F - in the confined interplanar space is rate-determining for the etching reaction. The expansion of interlayer spacing by polyols effectively reduces the diffusion activation energy of F - and accelerates the etching reaction.

Nitrogen-doped carbon materials (NCs) are extensively studied for the oxygen reduction reaction (ORR). However, the nature of active sites of pyridinic nitrogen (N P ) or graphitic nitrogen (N G ) on NCs is still under debate. Herein, we demonstrated that the ORR activity of NCs in alkaline media depended on the electronic synergism between N P and N G , rather than any single type of N. We measured the transferable electrons of NCs by absorption spectroscopy using 7'7'8'8-tetracyanoquinodimethane as an electron acceptor. The transferable electron amount of NCs is relevant to either N P or N G , leading to the [N P ] : [N G ] ratio as an electron transfer descriptor of NCs in a reverse volcano curve manner across nineteen NCs. The similar dependence of ORR activity on the [N P ] : [N G ] ratio of NCs was also discovered, demonstrating the synergistic effect of N P and N G . These results provide a new angle to understand the nature of ORR activity of NCs and optimize the ORR catalyst.