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Inverse gas chromatography (IGC) was employed in evaluating the catalytic surface of meso-microporous KIT-6 impregnated Ni (0.5–2.0 wt%) in methane dry reforming reaction. The free energy of adsorption did not changed significantly for the sample modified with highly dispersed Ni species (0.5 wt%). At higher Ni loadings, higher free energy of adsorption and enthalpy of adsorption of the probes were observed, together with high dispersive interaction and specific interaction of aromatics. The results indicated that during the impregnation, Ni species preferably penetrated into the microporous region to form Ni particles and became ‘unaccessible’. This feature was used to understand the dependence of activity on Ni loading for the gas phase catalytic methane reforming with carbon dioxide on Ni/KIT-6. The lower TOF at low metal loadings was attributed to Ni particles located in the micropores which result in diffusional constraint of reactants and products. [ABSTRACT FROM AUTHOR]

The mesocellular silica foams (MCF) supported rhodium catalysts, prepared by wetness impregnation method, were tested in CH 4 reforming with CO 2 . Hydrogen temperature-programmed desorption (H 2 -TPD) analysis showed that hydrogen spillover occurs on MCF loaded with highly dispersed rhodium. The turnover frequency of CH 4 (TOF CH4 (s −1 )) increased with the strength rise of spilt-over hydrogen. The promotion mechanism was investigated by controlled atmosphere 13 C and 1 H MAS NMR. The spilt-over hydrogen atoms were found to adsorb on the bridged oxygen sites (Si O Si) of MCF and to form surface terminal silanol groups. Meanwhile, in the reforming reaction steps, CH 4 dissociation into CH 3 * and CH 3 O* decomposition into CH 2 O* occurred. The results confirmed that hydrogen atoms can spill over from highly dispersed rhodium species to the neighboring bridged oxygen atoms of MCF, which promotes the reaction by facilitating rate determining steps of CH 4 dissociation and CH x O*( x = 2, 3) intermediates decomposition on metal surface. [ABSTRACT FROM AUTHOR]

Highlights: [•] La2O3-modified Ni/SBA-15 catalysts were studied in CH4 reforming with CO2. [•] Ni dispersion and the catalytic performance were improved with La addition. [•] The promoting intermediates were trapped in a designed infrared cell. [•] La promotes the reforming mainly by adsorbing CO2 and facilitating CO* and CH x O*. [ABSTRACT FROM AUTHOR]

Highlights: [•] IGC was used to study surface property of MCF loaded with the sized Ni particle. [•] High adsorption free energy and heat of aromatics on MCF with ca. 5nm Ni particle. [•] Strong dispersive and specific interaction on MCF with small Ni particle (<1.4nm). [•] Ni highly dispersed on MCF promotes the great interaction with aromatics structure. [Copyright &y& Elsevier]

Abstract: The pore structure of mesoporous silica KIT-6 has been systematically tuned via the variation of calcination temperature (773–1223K), with the mesopore size ranging from 4.8 to 7.5nm and micropore volume from 0.000 to 0.078cm3/g, respectively. Four n-alkanes (C6–C9), cyclohexane, benzene, toluene, trichloroethylene, and tetrachloroethylene were employed as probe molecules in the evaluation of the pore structure effect on KIT-6 surface property using inverse gas chromatography (463.2–493.2K). High free energy of adsorption and enthalpy of adsorption were observed on the KIT-6 with the micropore volumes. The dispersive interaction parameter , and specific interaction parameter I SP, were found to decrease with the increment of the mesopore size of the samples. These results indicate that the occurrence of micropore contributes the adsorption, while the narrow mesopore of KIT-6 promotes the dispersive and specific interaction. [Copyright &y& Elsevier]

Abstract: The mechanism of methane reforming with carbon dioxide over 1.0wt.% Rh/SBA-15 catalyst has been studied by the 13C and 1H magic-angle spinning (MAS) NMR spectroscopies under controlled atmosphere condition using 13CH4 + 12CO2 and 12CH4 + 13CO2 as reactants. The effect of temperature in the region of 298–1023K on the reaction was investigated and the contents of various 13C and 1H species were obtained quantitatively by the NMR technique. When treated at 573K, the carbon exchange between methane and carbon dioxide can be observed. With the temperature rising to 773K, the adsorbed CH3O* species is formed but no reforming reaction occurs. In the high temperature range of 873–1023K, the reforming reaction was observed with concomitant appearance of the adsorbed CH2O* species and the intensity of both CH3O* and CH2O* increases with increasing temperature, indicating that the decomposition of CH3O* to CH2O* occurs and the products of dry reforming are formed from decomposition of the adsorbed CH2O* species. [Copyright &y& Elsevier]

Abstract: Novel hybrid membranes were prepared by incorporating H-β-zeolite or Rh-loaded H-β-zeolite (Rh/H-β-zeolite) into polyvinyl chloride (PVC) for the pervaporative separation of benzene and cyclohexane. The membranes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to assess their morphology. The characteristics of these membranes for separating benzene/cyclohexane mixtures were investigated by varying zeolite content, feed composition and operating temperature. The results showed a typical trade-off curve; fluxes increased and selectivity decreased with the increase of benzene concentration in feed composition. The pervaporation performance for membranes filled with Rh/H-β-zeolite was much better than that for pure PVC membrane and membranes filled with H-β-zeolite. It might be caused by the special interaction between benzene and Rh/H-β-zeolite found by IGC previously. And the membrane containing 7wt.% of Rh/H-β-zeolite showed the highest separation selectivity of benzene at all feed compositions. From the temperature-dependent permeating values, the Arrhenius activation parameters were estimated. The resulting lower apparent activation energy values for permeation flux obtained for the Rh/H-β-zeolite-filled membranes compared to the H-β-zeolite-filled membranes were attributed to the special interaction between Rh/H-β-zeolite and benzene. [Copyright &y& Elsevier]

Abstract: Catalysts containing rhodium (Rh) were prepared by the wet impregnation method using H-β-zeolite as support. Retention time of three n-alkanes (C5–C7), cyclohexane, benzene, trichloroethylene and tetrachloroethylene on the Rh/H-β-zeolite catalysts (0.5–2.0wt% of Rh) and H-β-zeolite were measured by inverse gas chromatography (IGC) in the 473.2–513.2K temperature range. Standard free energy of adsorption, dispersive component of surface free energy of adsorbent and specific interaction parameters between polar probes and catalysts were evaluated. The results indicate that the adsorption characteristics of H-β-zeolite can be modified by rhodium. Surface area, enthalpy of adsorption and dispersive component of surface free energy decrease after the impregnation of rhodium. Besides, it was found that rhodium dispersed in the framework of H-β-zeolite had special adsorption for benzene which may be useful for making catalysts for certain reactions involving benzene in the future. [Copyright &y& Elsevier]

Facing greenhouse effects and the rapid exhaustion of fossil fuel, CO2 electrochemical reduction presents a promising method of environmental protection and energy transformation. Low onset potential, large current density, high faradaic efficiency (FE), and long-time stability are required for industrial production, due to economic costs and energy consumption. This minireview showcases the recent progress in catalyst design and engineering technology in CO2 reduction reaction (CO2RR) on copper based-catalysts. We focus on strategies optimizing the performance of copper-based catalysts, such as single-atom catalysts, doping, surface modification, crystal facet engineering, etc., and reactor design including gas diffusion layer, membrane electrode assembly, etc., in enhancing target electroreduction products including methane, methanol, ethylene, and C2+ oxygenates. The determination of the correlation and the developed technology might be helpful for future applications in the industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnO-CdS-Cu nanocomposite was synthesized through ZnO nanoparticle modification. • Photo-absorption and the transfer of photogenerated carriers were facilitated. • Substantial enhancement of the CO partial current density under 1-sun than the dark. • Wide ratio of CO and H 2 in the syngas product from 0.03 to 0.53. Syngas, the mixture of CO and H 2 , is an important feedstock for producing methanol and other liquid fuels. Herein, we demonstrated a photoelectrochemical system by employing cadmium sulfide (CdS)-decorated zinc oxide (ZnO) nanoparticles and Cu nanorods to boost the photoelectrochemical reduction of carbon dioxide (CO 2) in an aqueous solution. Structural characterizations showed that the heterostructure and interfaces of semiconductors facilitated the photo-absorption as well as the fast transfer of photogenerated carriers from the semiconductors to catalytic sites. Compared to the condition with light off, the tri-component ZnO–CdS–Cu catalyst exhibited an enhancement of 6.2 times in the CO partial current density at relatively low applied potential of –1.16 V versus reversible hydrogen electrode under ∼1 sun illumination. In addition, the ratio of CO and H 2 in the products was tuned in a wide range between 0.03 and 0.53, which was beneficial for the syngas production. [ABSTRACT FROM AUTHOR]

[Display omitted] The renewable energy-powered electroreduction of carbon dioxide or monoxide (CO) has been emerging as an attractive means to decarbonize the emission-intensive chemical manufacturing, which heavily relies on fossil fuels nowadays. One potential approach to promote the activity of electrocatalysts is to construct hybrid interface that can increase the stability of intermediates on electrode surfaces. Herein we developed a copper nanoparticle/polypyrrole (Cu-Ppy) nanowire composite as an efficient electrocatalyst for electrochemical CO reduction reaction. Compared to pure Cu nanoparticles, the Cu-Ppy composite exhibited a dramatically enhanced Faradaic efficiency of converting CO to ethylene (C 2 H 4) from 34% to 69% at −0.78 V vs. reversible hydrogen electrode (RHE) in KOH electrolyte, and an excellent C 2 H 4 partial current density of 276 mA·cm−2 at −1.18 V vs. RHE. Density functional theory calculations showed that the Cu-Ppy composite could bind CO more strongly as compared to pure Cu. As the Ppy coating allowed to stabilize OCCO*, a key intermediate in the C 2 H 4 formation, both the activity and selectivity of Cu-Ppy for CO-to-C 2 H 4 were increased. Our work suggests that constructing rationally designed hybrid interface can tune the local environment of catalyst surface toward enhanced activity and product selectivity. [ABSTRACT FROM AUTHOR]

Electroreduction of CO2 to multi‐carbon (C2+) products is a promising approach for utilization of renewable energy, in which the interfacial water quantity is critical for both the C2+ product selectivity and the stability of Cu‐based electrocatalytic sites. Functionalization of long‐chain alkyl molecules on a catalyst surface can help to increase its stability, while it also tends to block the transport of water, thus inhibiting the C2+ product formation. Herein, we demonstrate the fine tuning of interfacial water by surface assembly of toluene on Cu nanosheets, allowing for sustained and enriched CO2 supply but retarded water transfer to catalytic surface. Compared to bare Cu with fast cathodic corrosion and long‐chain alkyl‐modified Cu with main CO product, the toluene assembly on Cu nanosheet surface enabled a high Faradaic efficiency of 78 % for C2+ and a partial current density of 1.81 A cm−2. The toluene‐modified Cu catalyst further exhibited highly stable CO2‐to‐C2H4 conversion of 400 h in a membrane‐electrode‐assembly electrolyzer, suggesting the attractive feature for both efficient C2+ selectivity and excellent stability. [ABSTRACT FROM AUTHOR]

Electroreduction of CO2 to multi‐carbon (C2+) products is a promising approach for utilization of renewable energy, in which the interfacial water quantity is critical for both the C2+ product selectivity and the stability of Cu‐based electrocatalytic sites. Functionalization of long‐chain alkyl molecules on a catalyst surface can help to increase its stability, while it also tends to block the transport of water, thus inhibiting the C2+ product formation. Herein, we demonstrate the fine tuning of interfacial water by surface assembly of toluene on Cu nanosheets, allowing for sustained and enriched CO2 supply but retarded water transfer to catalytic surface. Compared to bare Cu with fast cathodic corrosion and long‐chain alkyl‐modified Cu with main CO product, the toluene assembly on Cu nanosheet surface enabled a high Faradaic efficiency of 78 % for C2+ and a partial current density of 1.81 A cm−2. The toluene‐modified Cu catalyst further exhibited highly stable CO2‐to‐C2H4 conversion of 400 h in a membrane‐electrode‐assembly electrolyzer, suggesting the attractive feature for both efficient C2+ selectivity and excellent stability. [ABSTRACT FROM AUTHOR]

[Display omitted] The electrochemical methane oxidation reaction is a potential approach for upgrading the nature-abundant methane (CH 4) into value-added chemicals, while the activity and selectivity have remained substantially low due to the extremely inert chemical property of CH 4. Inspired by the methane mono-oxygenase in nature, we demonstrated Mg-substituted metal–organic frameworks (Mg-MOF-74) containing a uniform distribution of Mg-oxo-Mg nodes as efficient catalytic sites. Compared to MgNi-MOF-74 and Mg(OH) 2 without the Mg-oxo-Mg nodes, the Mg-MOF-74 presented a much enhanced CH 4 electrooxidation performance, with a unique selectivity of producing formate. The maximum Faradaic efficiency of all liquid products reached 10.9% at 1.60 V versus reversible hydrogen electrode (RHE), corresponding to the peak production rate of 126.6 μmol·h−1·g−1. [ABSTRACT FROM AUTHOR]

Abstract: P–Mo–V mixed oxide-incorporating mesoporous silica catalysts with different contents were prepared by a template method with Keggin-type heteropoly acid (HPA), H5PMo10V2O40, under acidic conditions, followed by calcination at 873K for 5h. During the preparation, the HPA used as a precursor of the oxide acted as a co-acid of HCl that controlled the acidity of the starting mixture. The catalysts were characterized by thermal analysis, X-ray diffraction, X-ray fluorescence spectroscopy, N2 adsorption, transmission electron microscopy, and Raman spectroscopy. The results indicated that the framework of P–Mo–V incorporated mesoporous silicas was similar to that of MCM-48. The molar ratio of P:Mo:V (1:10:2) in the catalysts showed no significant change from the HPA precursor and the mixed oxides were highly dispersed below 6.68wt% content. The catalysts showed good activity in the selective oxidation of methane to formaldehyde with oxygen. [Copyright &y& Elsevier]

Abstract: The effect of tin on the structure, acidity, and water adsorption property of Nb2O5/α-Al2O3 catalyst and on this catalyst''s performance for ethylene oxide (EO) hydration were studied by XRD, Raman spectroscopy, NH3-TPD, IR of pyridine and of H2O adsorption, and catalytic tests. Characterization results revealed that the density of acidic sites decreased with the addition of tin and with increasing Sn/Nb ratio in the cases studied, whereas the acidity exhibited minimum strength at . The IR of water adsorption indicated that addition of tin significantly enhanced the water adsorption property of the catalyst. The catalytic tests revealed that monoethylene glycol (MEG) selectivity increased from 89.8% of the Nb2O5/α-Al2O3 catalyst to 94.0% of the tin-promoted catalyst maintaining the EO conversion at 99.7%, and the catalyst exhibited excellent stability. The enhanced water adsorption property of the tin-promoted catalyst is proposed to be responsible for the significant improvement in MEG selectivity. [Copyright &y& Elsevier]

• CoMg/Al 2 O 3 was synthesized by the wetness impregnation method. • IGC was used to study the surface properties of CoMg/Al 2 O 3. • Dispersive and specific components are enhanced after Co and Mg impregnation. • CoMg/Al 2 O 3 presents high activity in aerobic oxidation of p -cresol into p -HBA. • Medium adsorption of p -cresol and strong stabilization of intermediates are involved. The surface properties of CoMg/Al 2 O 3 were evaluated in the aerobic oxidation of p -cresol. The surface interaction is enhanced greatly after Co and Mg impregnation with the mole ratio of Co/Mg from 2 : 1 and 2 : 3. The strongest interaction for the nonpolarity and benzene ring was found on CoMg/Al 2 O 3 with Co/Mg of 2 : 3. But for the interaction with p -π group bonding with negative anion, the highest value appears on the catalyst with the Co/Mg of 2 : 2. In aerobic oxidation of p -cresol, the conversion is significantly increased with Co addition and reaches around 60 % after 24 h' reaction at 338 K. The highest selectivity of p -hydroxybenzaldehyde of 99 % is achieved on Al 2 O 3 with the co-impregnation mole ratio of Co/Mg of 2 : 2. It is suggested that medium adsorption of the reactants and strong stabilization of the intermediates facilitate the aerobic oxidation of p -cresol to p -hydroxybenzaldehyde. [Display omitted] [ABSTRACT FROM AUTHOR]

The electrochemical dinitrogen reduction represents an attractive approach of converting N 2 and water into ammonia, while the rational design of catalytic active centers remains challenging. Investigating model molecular catalysts with well-tuned catalytic sites should help to develop a clear structure-activity relationship for electrochemical N 2 reduction. Herein, we designed several polycyclic aromatic hydrocarbon (PAH) molecules with well-defined positions of boron and nitrogen atoms. Theoretical calculations revealed that the boron atoms possess high local positive charge densities as Lewis acid sites, which are beneficial for N 2 adsorption and activation, thus serving as major catalytic active sites for N 2 electrochemical reduction. Furthermore, the close vicinity of two boron atoms can further enhance the local positive density and subsequent catalytic activity. Using the PAH molecule with two boron atoms separated by two carbon atoms (B-2C-B), a high NH 3 production rate of 34.58 μg·h−1·cm−2 and a corresponding Faradaic efficiency (5.86%) were achieved at −0.7 V versus reversible hydrogen electrode, substantially exceeding the other PAHs with single boron or nitrogen-containing molecular structures. [ABSTRACT FROM AUTHOR]

Electrochemical CO 2 reduction with rationally designed copper-based electrocatalysts is a promising approach to reduce CO 2 emission and produce value-added products. Grain boundaries and micron-strains inside catalysts have been proposed as active catalytic sites, while the controlled formation of these sites has remained highly challenging. In this work, we developed a strategy of creating high-density grain boundaries and micron-strains inside CuO electrocatalysts by fast cooling with liquid nitrogen. Compared to samples with slower cooling rates, the fast cooled CuO showed clear difference in their crystal domain sizes, micro-strain densities, and the chemisorption capacities of CO 2 and CO. This micro-strain-rich CuO electrocatalyst exhibited a high total current density over 300 mA·cm−2, and an outstanding Faradaic efficiency for C 2 products (with a majority to ethanol) at −1.0 V vs. reversible hydrogen electrode. Our work suggests a facile approach of tuning grain boundaries and micro-strains inside Cu-based electrocatalysts to scale up electrochemical CO 2 reduction for high value-added products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co nanoclusters were in situ formed in aerobic oxidation of cis -cyclooctene. • Cyclooctene dimer oxide is formed to stabilize the clusters as a surfactant. • Efficient for soluble Co clusters in aerobic oxidation of α-C H of ethylbenzene. • TON of acetophenone yield on Co clusters is 960 times more active than Co salt. • In situ formed Co nanocluster is extended to aerobic oxidation of cyclohexene. Aerobic oxidation of α-C H bond of organic compounds to valuable chemicals is widely investigated in both fundamental research and industry. Due to the good stability of molecular oxygen, severe reaction conditions are generally required. Herein, by in situ synthesis we used molecular oxygen to induce cobalt nanoclusters with the sensitive catalysis in mild selective oxidation. The cobalt containing clusters with an average diameter around 0.9 nm are in situ prepared in the presence of cis -cyclooctene epoxidation and cyclooctene dimer oxide is formed at the interface to stabilize Co clusters with electron donation as an oil-soluble surfactant. The soluble clusters exhibit high activity in selective oxidation of α-C H bond of ethylbenzene into acetophenone and turnover number (TON) reaches about 7 × 104 during 50 h' reaction at 373 K, which is around 960 times more active than the one using CoCl 2 salt as the catalyst, resulting from efficient mass transportation, π bond interaction and oxygen gas activation. Extended work based on this understanding demonstrates that cobalt nanoclusters also effectively catalyze aerobic oxidation of cyclohexene. [ABSTRACT FROM AUTHOR]

Abstract: Rational design of electrocatalysts toward efficient CO2 electroreduction has the potential to reduce carbon emission and produce value‐added chemicals. In this work, a strategy of constructing 2D confined‐space as molecular reactors for enhanced electrocatalytic CO2 reduction selectivity is demonstrated. Highly ordered 2D nanosheet lamella assemblies are achieved via weak molecular interaction of atomically thin titania nanosheets, a variety of cationic surfactants, and SnO2 nanoparticles. The interlayer spacings can be tuned from 0.9 to 3.0 nm by using different surfactant molecules. These 2D assemblies of confined‐space catalysts exhibit a strong size dependence of CO2 electroreduction selectivity, with a peak Faradaic efficiency of 73% for formate production and excellent electrochemical stability at an optimal interspacing of ≈2.0 nm. This work suggests great potential for constructing new molecular‐size reactors, for highly selective electrocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

Cr adsorption on wood-based powdered activated carbon (WPAC) was characterized by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The highest Cr(VI) adsorption (40.04%) was obtained under acidic conditions (pH 3), whereas Cr removal at pH 10 was only 0.34%. The mechanism of Cr(VI) removal from aqueous solutions by WPAC was based on the reduction of Cr(VI) to Cr(III) with the concomitant oxidation of C-H and C-OH to C-OH and C=O, respectively, on the surface of WPAC, followed by Cr(III) adsorption. Raman spectroscopy revealed a change in the WPAC structure in terms of the D/G band intensity ratio after Cr(VI) adsorption. SEM-EDS analysis showed that the oxygen/carbon ratio on the WPAC surface increased from 9.85% to 17.74%. This result was confirmed by XPS measurements, which showed that 78.8% of Cr adsorbed on the WPAC surface was in the trivalent state. The amount of oxygen-containing functional groups on the surface increased due to the oxidation of graphitic carbons to C-OH and C=O groups. [ABSTRACT FROM AUTHOR]

Abstract: Hollow microspheres of ZSM-5 with a mesoporous shell have been synthesized through formation of amorphous hollow SiO2/Al2O3 microspheres by sol–gel process in multiple oil–water–oil emulsions and transformation of the amorphous species into zeolite by water–organic vapor-phase transport treatment at 160°C for 8days. The morphology of the amorphous and zeolite spheres observed by scanning electron microscopy shows no significant change whereas the molar ratio of Si/Al increases from 6 to 20 during the transformation. The structural feature of zeolite was characterized by X-ray diffraction and 29Si and 27Al magic-angle spinning nuclear magnetic resonance. Transmission electron microscopy and N2 adsorption–desorption isotherms indicate that uniform mesopores in the shell of zeolite spheres arise from the interstices among zeolite crystallites. [Copyright &y& Elsevier]

Commercial fillers are widely used in the industrial manufacturing of silicone-based sealants such as CaCO 3 filled polydimethylsiloxane (PDMS). The surface property of calcium carbonate, which is readily influenced by the adsorbed water and chemical modifiers, results in different rheological performances of the composites. However, it is difficult to characterize the surface due to the multiple contributions from the morphology, functional groups, and pore structure. In this work, the surface property was differentiated by the surface energies using inverse gas chromatography (IGC). The dispersive interaction was determined by n -alkanes (C 7 -C 10), and the specific components were evaluated by cyclohexane, benzene, trichloroethylene, and tetrachloroethylene. The calcium carbonates showed the different dispersive interaction and the varied specific component on the modified surface. It was suggested that the dispersive interaction between calcium carbonate fillers and PDMS impacted the viscosity of the formed composite. [Display omitted] • Similar structure and morphology for the commercial CaCO 3 fillers. • Different DOP absorption of the fillers and varied rheology for the filled PDMS. • IGC was used to study the surface property of the modified CaCO 3. • Varied dispersive and specific components of surface energy for CaCO 3 fillers. • Strong dispersive interaction promotes the interface interaction of the composites. [ABSTRACT FROM AUTHOR]

Silver-containing material is one of the efficient electrocatalysts in converting CO 2 into CO, but competing hydrogen evolution reaction (HER) in aqueous solutions results in poor energy efficiency. Here, Ag 3 subnanoclusters with the structure sensitive to CO 2 activation are in situ prepared by the cyclohexene oxidation. Hydrophobically modified Ag nanomaterials with an average particle size from 1.0 to 3.3 nm are water-repulsive, organic-soluble, and composited of the Ag 3 cluster units, possessing the electron donation and strong chemical adsorption of CO 2. In the electroreduction of CO 2 , a high mass activity about 10,200 A cm−2 g Ag −1 is achieved for CO production at −1.4 V vs. reverse hydrogen electrode (RHE) on Ag nanoclusters with the external size of 1.9 nm, exhibiting 20 times higher than commercial Ag nanoparticles (diameters of 60–120 nm). Electrochemical tests in flow cells show an excellent mass activity of 55,000 A cm−2 g Ag −1 with a large current density of around 30 mA cm−2 for the CO production at −0.71 V vs. RHE, much higher than the previously reported Ag catalysts. Hydrophobically made Ag 3 subnanoclusters facilitate the CO 2 electroreduction to CO in aqueous solutions through accelerating the electron donation and suppressing the side reaction of water reduction. • Hydrophobically modified Ag 3 nanoclusters were employed in aqueous electroreduction of CO 2. • Mass activity for CO on Ag nanoclusters is 20 times more active than nanoparticles. • 55,000 A cm−2 g Ag −1 and 30 mA cm−2 for CO production at −0.71 V in the flow cell. • Ag 3 nanocluster facilitates the CO 2 electroreduction and suppresses H 2 O reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon black was doped by chlorine via a hydrothermal process. • Surface charge density was polarized by the chlorine dopant. • Efficient for NRR with an NH 3 production rate of 4.3 μg h−1 cm–2 (FE 7.2%). • Well catalytic performance was achieved on metal-free doping carbon black. The electrochemical reduction of stable dinitrogen (N 2) molecules into value-added chemicals such as ammonia has been attracting substantial research interests recently, while the bottleneck of catalyst design exists in the rational synthesis of catalytic centers with efficient N 2 chemisorption and subsequent activation. In this work, we demonstrated a facile approach of doping carbon black with a trace amount of chlorine, which allowed for the enhancement of its nitrogen reduction capability. Structural characterizations revealed the successful doping of the chlorine element into the carbon framework, accompanied by the polarization of the surface charge density. The positively charged carbon sites behaved as good NRR catalytic centers, with a maximum ammonia production rate of 4.3 μg h−1 cm–2 and a corresponding Faradaic efficiency of 7.2%, thus suggesting a potential approach for enhancing the nonmetal catalysts for electrochemical ammonia synthesis. [ABSTRACT FROM AUTHOR]

Co, Ni‐based (hydr)oxides with stoichiometric or nonstoichiometric composites are playing significant roles in renewable energy technologies, such as electrocatalytic reactions for transforming earth abundant resources into value‐added chemicals. In the past several years, attributed to the development of novel synthesis strategies, characterization techniques, and theoretical calculations, the rational design and realization of a variety of Co, Ni‐based (hydr)oxides with exciting performances have been demonstrated. Particularly, the electrocatalytic reactivities of these Co, Ni‐based (hydr)oxides are highly dependent on their surface electronic structures, which can be well tuned by their nanostructures and compositions. This Review summarizes recent research advances in regulating electronic structures toward the optimization of electrochemical reactivity in aqueous solutions. These research works mainly focus on three important clean energy reactions: i) water oxidation, ii) oxygen reduction, and iii) carbon dioxide reduction, where the developments of advanced electrocatalysts can enable the production of value‐added chemicals or fuels. Furthermore, the electronic structure–property relationships behind the enhanced electrocatalytic properties of these Co, Ni‐based (hydr)oxides are also discussed. This Review covers recent research advances in regulating electronic structures toward the optimization of electrochemical reactivity in aqueous solutions, mainly focusing on three important clean energy reactions: i) water oxidation, ii) oxygen reduction, and iii) carbon dioxide reduction. [ABSTRACT FROM AUTHOR]

The continuous increase of CO2 concentration in the atmosphere has been imposing an imminent threat for global climate change and environmental hazards. In recent years, the electrochemical or photochemical conversion of CO2 into value‐added chemicals or fuels has received significant attention, as it may enable an attractive means to mitigate the atmospheric CO2 concentration and complete the imbalanced carbon‐neutral energy cycle, as well as create renewable energy resources for human use. Among the different electrocatalysts being studied, Cu‐based materials have been demonstrated as the only category of candidates that allows the conversion of CO2 into a variety of reducing products, including carbon monoxide, hydrocarbons, and alcohols. Herein, the reaction pathways for different Cu‐based catalysts for C1 and C2+ products are introduced. Then, different parameters in tuning Cu‐based electrocatalysts are summarized and discussed, including the morphologies, compositions, crystal facets, and oxide derivation. In addition, various types of parameters for CO2 electroreduction are also described, particularly the option of electrolytes such as aqueous, ionic liquids, and organic solutions. Finally, the current challenges are discussed and the potential strategies to facilitate the future development of CO2 electroreduction are summarized. Copper‐based nanomaterials are promising catalysts for electrocatalytic CO2 reduction with potential selectivity toward hydrocarbons and alcohols. Diverse approaches for enhancing the performance of copper‐based catalysts are reviewed, including studies on morphology, crystal facets, oxide‐derived Cu, compositional effect, and electrolytes. The current challenges and perspectives are also discussed. [ABSTRACT FROM AUTHOR]