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Graphical abstract Highlights • Pd nanoparticles supported on carbon black were encapsulated by mesoporous silica. • The 3D nature of interconnecting pores was confirmed by electron tomography. • The covered catalyst resists sintering but the underlying active phase is accessible. • The catalyst is performant in glucose oxidation due to improved hydrophilicity. Abstract Palladium nanoparticles supported on carbon black were encapsulated in a thin mesoporous silica layer. APTES ((3-aminopropyl) trimethoxysilane) was used as anchoring agent to ensure robust and homogeneous formation of a mesoporous SiO 2 layer around the supported catalyst. This was confirmed by XPS, TEM, electron tomography and nitrogen physisorption measurements. The covered catalyst was tested in the oxidative dehydrogenation of glucose into gluconic acid: the high catalytic activity was maintained in comparison with uncovered catalyst, indicating that the underlying active phase was still available. In addition, the silica layer leads to high temperature stability which prevents the agglomeration of palladium nanoparticles upon sintering conditions. [ABSTRACT FROM AUTHOR]

Increasing the amount of accessible active sites to reactants is an effective way to enhance electrocatalytic activity. Although single-atom catalysts are claimed to be capable of achieving 100% atomic utilization, there may be abundant single-atom sites buried and inaccessible to reactants in practice. Herein, two Ni, N-doped carbon catalysts with Ni-N x atomic sites are comparatively studied for CO 2 electroreduction. In contrast to the Ni-N x /Carbon nanosheets with Ni loading of 2.42 wt%, the Ni-N x /Carbon black with lower Ni loading of 0.16 wt% excitingly exhibits higher activity for CO production. The atomically dispersed Ni-Nx sites over carbon black surface benefit the exposure and utilization of single-atom sites, leading to a significant increase of TOF from 2140 to 100,347 h−1 at − 0.8 V. Particularly, an extraordinarily high current density up to 300 mA cm−2 with CO selectivity of ∼100 % are achieved for Ni-N x /CB in the flow cell. This work demonstrates the significance of increasing single-atom site utilization. [Display omitted] • Ni-Nx/CNS and Ni-Nx/CB catalysts with Ni-Nx sites are synthesized for CO2RR. • Ni-Nx/CB catalyst exhibits high CO selectivity and TOF for CO2 conversion. • Ni-Nx/CB catalyst with low Ni loading exhibits high single-Ni-atoms utilization. • High current density of > 300 mA cm-2 is achieved in the flow cell. [ABSTRACT FROM AUTHOR]

The two-electrons (2e–) oxygen reduction reaction (ORR) offers a sustainable and decentralized alternative to the traditional synthetics for hydrogen peroxide (H 2 O 2) production. Although various Co single atom catalysts (SACs) have been proposed as highly effective 2e– ORR catalysts, there is still room for improvement through fine-tuned coordination environment. Here, a Co-N 5 -O-C with the combination of highly coordinated Co-N 5 moieties and nearby electro-withdrawing epoxides is first time developed to reach the optimal binding energy of *OOH intermediate, resulting in the ultrahigh mass activity of 87.5 A g−1 at 0.75 V vs. RHE. Moreover, a high H 2 O 2 production rate of 11.3 mol g−1 h−1 at 200 mA cm−2 is also obtained by a flow cell device. Such an efficient in-situ generation of H 2 O 2 further enables 100% degradation of the organic methylene blue pollutant within 15 min through the electro-Fenton process. These findings will provide a new direction for on-site H 2 O 2 synthesis and wastewater treatment. [Display omitted] • Penta nitrogen coordinated Co single-atom catalyst with rich-epoxy groups is synthesized. • DFT calculation reveals Co-N 5 with epoxy oxygen has the most favorable binding energies of *OOH for 2e- ORR. • Up to 85.6% high selectivity and ultrahigh mass activity of 87.5 A g−1 for H 2 O 2 production can be reached. • Outstanding H 2 O 2 production rate of 11.3 mol g−1 h−1 is achieved under high current density using a flow cell. • Effective organic MB pollutant degradation is demonstrated using an electro-Fenton system. [ABSTRACT FROM AUTHOR]

Supported ordered intermetallic nanoparticles are of significant interest for catalysis applications owing to their unique surface/near-surface structures and electronic properties. However, the synthesis of small-sized intermetallic catalysts with high mass activity remains a formidable challenge, as high temperatures annealing treatments are generally requisite to achieve ordered intermetallic structures but lead to undesired larger crystallites. Here, we report an industrially relevant impregnation approach for the scalable synthesis of small-sized platinum-based intermetallic nanoparticle catalysts by regulating inter-particle distance on carbon black supports to mitigate metal sintering in high-temperature annealing. We construct a library consisting of 18 binary Pt-based intermetallic nanoparticle catalysts with an average size of < 5 nm. The prepared intermetallic catalyst libraries exhibit outstanding proton-exchange-membrane fuel cells performance, including high mass activities of 1.3–1.8 A mg Pt –1, large peak power densities of 1.2–1.4 W cm–2 in H 2 -air cells, and efficient Pt utilization of ∼0.07 g kW–1 at rated power. [Display omitted] • Intermetallic compounds (IMC) have unique strain/electronic effects in catalysis. • A family of small size Pt-based IMCs was achieved by regulating inter-particle distance. • Small size and ordered IMC structure guarantee outstanding performance in fuel cell. [ABSTRACT FROM AUTHOR]

A magnetically separable core-shell-like catalyst Ni-Pd/CB is designed and synthesized via a facile sequential reduction strategy. It is found that the Pd nanocrystals with a thickness of ∼1.67 nm and a length of ∼7.92 nm are intimately coupled with the Ni cores and the formed core-shell-like Ni-Pd nanoparticles are well dispersed on the CB surface with much smaller particle size and narrower size distribution as compared with that of unsupported ones. The ligand-free Ni-Pd/CB nanocatalyst is evaluated for Suzuki-Miyaura coupling reaction and exhibits excellent catalytic activity under mild aerobic conditions without using toxic solvents and inert protective atmosphere, achieving green catalysis. The high catalytic performance of Ni-Pd/CB catalyst can be attributed to its unique core-shell-like nanostructure and the concerted effects between the individual components. The introduction of Ni not only makes the catalyst magnetically separable in a suspension system, but also significantly lowers the cost. [ABSTRACT FROM AUTHOR]

Electrochemical production of H 2 O 2 from O 2 via the two-electron reaction pathway (2e-ORR) is a promising alternative to the energy- and organic pollutant-intensive industrial anthraquinone process. However, irrespective of numerous research efforts on catalyst design and remarkable advances made in this area, the catalysts displaying high H 2 O 2 production rate so far unexceptionally required expensive/hazardous catalyst precursors and involved tedious steps and/or harsh treating conditions. Herein, we report a slightly nitrogen-doped carbon 2e-ORR catalyst that was synthesized simply by pyrolyzing a polydopamine (PDA) coating on Vulcan XC72 carbon black (p -PDA/XC). In H 2 O 2 production via ORR in an acidic electrolyte, the catalyst showed 185 mV less overpotential than XC and remarkably high selectivity up to 96%. Highly efficient and durable H 2 O 2 production was demonstrated by the stable accumulation of H 2 O 2 to 1368 mmol g cat −1 within 8 h, translating to a H 2 O 2 production rate of 171 mmol g cat −1 h−1. A good linear relationship was identified between the H 2 O 2 partial current and the surface content of the C–O/C–N and C O species for the XC and p -PDA/XC catalysts, inferring that the C atoms in or adjacent to these species serve as the active sites for 2e-ORR to H 2 O 2. The inexpensive starting materials, facile synthetic strategy, and excellent catalytic performance of the p -PDA/XC catalyst may accelerate the establishment of an affordable, safe, and direct O 2 -to-H 2 O 2 electrochemical process. [Display omitted] • N-doped carbon catalysts were fabricated by pyrolyzing polydopamine on carbon black. • The as-synthesized p -PDA/XC catalysts were effective in electrocatalyzing O 2 to H 2 O 2. • p -PDA modification markedly reduced the overpotential and enhanced H 2 O 2 selectivity. • H 2 O 2 was stably produced within 8 h at a high rate of 171 mmol g cat −1 h−1. • H 2 O 2 partial current correlated linearly with the surface content of C–O/C–N and C=O. [ABSTRACT FROM AUTHOR]

Highlights: [•] Graphites and carbon blacks have been tested in the CWPO of phenol (C Phenol,0 =1g/L, 80°C). [•] Non-porous carbon blacks without mineral impurities are efficient and stable catalysts. [•] Low adsorption capacity prevents carbon deactivation by adsorbed oligomer by-products. [•] Total phenol conversion with 100% efficiency of H2O2 consumption was achieved in 20h. [ABSTRACT FROM AUTHOR]

Abstract: Ru/CeO2 catalysts with Ru loading of 1–5wt.% were prepared by wet impregnation from aqueous ruthenium (III) nitrosyl nitrate solution and activation with an air flow at 600°C for 4h. This activation resulted in a considerable reactivity for the catalytic oxidation of carbon black (CB) (T 50% ∼350°C “tight contact” mixtures and T 50% ∼515°C “loose contact” mixtures) and volatile organic compounds (VOCs) (T 50% =175°C for propene, T 50% =215°C for toluene). When carbon black oxidation was conducted under “propene (6000ppm)+air” or “toluene (2000ppm)+air” flow, the elimination of an important part of CB was observed at relatively low temperatures comparing to its elimination under pure air flow. These temperatures correspond to the total oxidation of the VOC present in the reactant gases. Carbon black total elimination was also investigated under isotherm conditions in the presence and in the absence of propene. Total elimination occurred during shorter times when combustion was performed under propene. TPR study showed that ruthenium species present in the catalysts after activation reduces at relatively low temperatures (<100°C) and that from a Ru loading of 1.5wt.%, agglomerated ruthenium oxide was formed and that this latter is more difficult to reduce (>100°C). [Copyright &y& Elsevier]

A comprehensive understanding on the selectivity toward electrocatalytic hydrogenation products of nitrobenzene was conducted experimentally and theoretically over a Cu3Pt/C alloying catalyst, revealing the significant role of the applied reduction potential and pH of electrolyte solution in regulating the product selectivity of nitrobenzene hydrogenation. [Display omitted] • High-efficiency Cu x Pt y /C alloying catalysts were fabricated for selective electrocatalytic hydrogenation of nitrobenzene. • The experimental and theoretical studies reveal Cu 3 Pt/C with superior electrocatalytic activity toward Ph-NO 2 hydrogenation. • The DFT calculations provide a comprehensive understanding on the selective electrocatalytic Ph-NO 2 hydrogenation mechanisms. We report ultrafine Cu x Pt y alloying nanoparticles anchored on carbon black (Cu x Pt y /C) for selective electrocatalytic hydrogenation of nitrobenzene (Ph-NO 2) at ambient conditions. The experimental and theoretical studies reveal that as electrocatalyst, the optimal Cu 3 Pt/C with adjusted electronic structure can effectively facilitate the adsorption and activation of Ph-NO 2. The results indicate that the acidic media is favorable for the production of aminobenzene irrelevant to the applied potential, while the electrocatalytic hydrogenation products are highly dependent on the reduction potential in the alkaline media. As a result, the Cu 3 Pt/C can afford almost 100 % conversion of Ph-NO 2 into azoxybenzene with ∼99 % selectivity at 0.3 V (vs. RHE) and aminobenzene with ∼99 % selectivity at -0.3 V (vs. RHE) in 1.0 M KOH, respectively. The theoretical calculations provide a comprehensive understanding of the selective electrocatalytic hydrogenation mechanisms of Ph-NO 2 relative to electrolyte pH and applied potential, matched well with the experimental results. [ABSTRACT FROM AUTHOR]

• Homogenous FeNi alloy catalysts with different atomic ratios were obtained by simple sol-gel method. • Synergistic effect in the FeNi alloy suppresses the oxidation of the Fe and Ni surface in the air. • Fe activates Ni atoms for efficient selective hydrogenation of glucose to sorbitol. • Synergistic effect only arises in FeNi alloy catalyst not in a mixture of Fe and Ni catalysts. Carbon black (CB) supported Ni, Fe, or Fe-Ni alloy catalysts were synthesized by sol-gel to elucidate the reaction pathways over each catalyst, as well as synergistic effects in glucose to sorbitol hydrogenation. The bimetallic materials presented small and alloyed nanoparticles that were richer in reduced metallic sites at the surface than their monometallic counterparts. Glucose isomerization to fructose was favoured over Fe/CB, while glucose hydrogenation to sorbitol is the dominating pathway over Ni/CB catalyst. By contrast, sorbitol production was promoted and undesired isomerization was suppressed when Fe and Ni formed a nanoalloy. In addition, the alloy catalyst presented better stability than the corresponding monometallic catalyst. A comparison with a mechanical mixture of Fe/CB and Ni/CB monometallic catalysts demonstrated the synergy at the nanoscale in the alloy. By comparing different Fe:Ni ratios, the 1:1 formulation was identified as the best compromise to achieve a high activity while maintaining high sorbitol selectivity. [ABSTRACT FROM AUTHOR]