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Electrochemical dechlorination reaction (EDR) is a promising, environmentally friendly, and economically profitable technology for treating chlorinated organic pollutants. For efficient environmental protection, electrocatalysts with high stability and low cost are of extremely significance to the development of EDR technology. Carbon-based materials have aroused broad interest as electrocatalysts for many electrochemical reactions due to their characteristics including large specific surface area, controllable structure, good conductivity, and chemical stability. For EDR, the carbon-based materials also show many unique superiorities, like strong adsorption capacity to chlorinated organic compounds (COCs), excellent catalytic activity and stability, and environmental compatibility. This review starts with a detailed summary on the mechanisms of electrochemical dechlorination (direct and indirect electron transfer pathway) and factors affecting the effectiveness of EDR. Then the paper comprehensively overviews the current progresses of carbon-based materials for EDR of COCs, following their two major application scenarios, i.e., directly as electrocatalysts and as advanced supports for other catalysts. Moreover, the formation of different active sites in carbon-based electrocatalysts and their EDR activities are analyzed. Finally, the current challenges and perspectives in this field are discussed. This review will provide an in-depth understanding for the design of advanced carbon-based materials and promote the development of EDR technology. [ABSTRACT FROM AUTHOR]

We have studied Cu–Zn and Cu–Ni containing catalysts on carbon supports based on IR-pyrolyzed chitosan and detonation nanodiamond (DND) and assessed their activity for the methanol steam reforming process. All of the catalysts have demonstrated rather high activity for this process and good stability over 30 h of continuous operation. The DND-based catalysts have been shown to have better performance, which seems to be due to their larger surface area and the nature of the functional groups on their surface. The activity of the bimetallic catalysts and the nature of the supports have been shown to be interrelated. [ABSTRACT FROM AUTHOR]

Catalytic conversion of biomass and waste into chemicals and fuels is gaining interest to reach a circular economy. Here, we review carbon-based and carbon-supported nanocatalysts for biomass conversion with focus on catalyst types and synthesis, optimization, mechanisms and three-dimension catalytic structures. Catalystic materials include amorphous carbon, graphene, graphene oxide, carbon nanotubes and carbon nanofibers. [ABSTRACT FROM AUTHOR]

The development of highly efficient Pt-based nanocatalysts is important for the commercialization of direct ethanol fuel cells (DEFCs) but remains challenging to achieve. Here in, we developed an ingenious strategy to significantly improve the electrocatalytic property of Pt-based catalyst towards ethanol oxidation reactions (EOR) in acid medium by doping tungsten. In this study carbon (Vulcan XC-72R, Ketjen black, carbon nanotubes) supported Pt-surface-enriched platinum–tungsten bimetallic nanoparticles (W@Pt/C, W@Pt/KJ, W@Pt/CNT) were prepared using the etching effect of galvanic replacement on amorphous tungsten nanoparticles. Additionally, no surfactant is used in the preparation of the catalysts. The catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. From the results, we can conclude that W@Pt nanoparticles were uniformly loaded on each carbon support. Finally, when compared with JM Pt/C, the catalytic activity of W@Pt/C was increased by 30% and the current density retained by W@Pt/C was 1.6 times that of the commercial catalyst (123 mA mgPt−1). At the end of the 3600 s reaction, W@Pt/C retained a current density of 198 mA mg−1 which is 1.6 times that of commercial catalyst JM Pt/C (123 mA mg−1). Also, W@Pt/KJ retained a current density of 176 mA mg−1 which is 1.4 times that of JM Pt/C. Furthermore, the metal oxides (WOX) in the catalyst can easily adsorb -OH species which can transform COads poisoning species to CO2, thus promoting the catalytic activity and stability toward EORs. [ABSTRACT FROM AUTHOR]

Catalytic layers on the surface of Toray Carbon Fiber Paper TGP-H-060 T and AVCarb® Carbon Fiber Paper P50 carbon carriers are formed by the ion-beam-assisted deposition of platinum and rare-earth-metal gadolinium (as an activating additive) in order to obtain electrocatalysts for the direct oxidation of ethanol and methanol for fuel cells with a polymer membrane electrolyte. The formation of the layers is carried out in the ion-beam-assisted deposition mode, in which metal deposition and mixing of the deposited layer with the substrate surface with accelerated (U = 5 kV) ions of the same metal are carried out, respectively, from the neutral fraction of the vapor and plasma of a vacuum pulsed arc discharge. The microstructure and composition of the obtained surface layers are studied using scanning electron microscopy, electron probe X‑ray spectral microanalysis, X-ray fluorescence analysis, and Rutherford backscattering spectrometry. As a result of the ionic mixing of all components, multicomponent layers containing atoms of precipitated metals and substrate elements, as well as oxygen impurities, are obtained. [ABSTRACT FROM AUTHOR]

Glycerol electrooxidation was evaluated on Pt electrodeposited over carbon Vulcan (CV), multi-walled carbon nanotubes (MWCNTs), graphene oxide nanoribbons (GONRs), and graphene nanoribbons (GNRs). Different masses of Pt were deposited under the same conditions, producing different surface areas of Pt. The presence of GNRs slightly enhanced the specific activity of the catalyst. By investigating the derivative voltammetry of glycerol, we found that the supports did not shift the onset potential towards lower values. Moreover, we found that the apparent activation energy did not vary by changing the carbon support. In this sense, we rationalized the slight improvement in specific activity of Pt deposited on GNRs as a consequence of the frequency of collision factor due to the availability of Pt over the longitudinal flat surface of nanoribbons, as shown by the high active surface area/mass of electrodeposited Pt ratio. [ABSTRACT FROM AUTHOR]

Catalytic layers are prepared by the vacuum ion-beam-assisted deposition of tin and platinum onto carbon-based AVCarb® Carbon Fiber Paper P50 and Toray Carbon Fiber Paper TGP-H-060 T supports to produce electrocatalysts for direct methanol and ethanol fuel cells with a polymer-membrane electrolyte. The layers are formed in the mode of ion-assisted deposition, wherein ions of the deposited metal are used as ions assisting deposition. Metal deposition is performed from a neutral vapor fraction, while mixing of the deposited layer with the substrate by accelerated ions of the same metal is carried out from the vacuum arc discharge plasma of a pulsed electric arc ion source. The morphology and composition of the layers is studied using scanning electron microscopy, electron probe microanalysis, X-ray fluorescence analysis, and Rutherford backscattering spectrometry. It is demonstrated by means of voltammetric measurements that the resulting electrocatalysts exhibit activity in the oxidation of methanol and ethanol. [ABSTRACT FROM AUTHOR]

The propensity of carbon support for methanation in a hydrogen-containing medium is a problem for active ruthenium ammonia synthesis catalysts, since this leads to the degradation of the support and the sintering of the active component. This review analyses some key works on approaches to methanation inhibition and their results to show that, on the whole, an algorithm for solving the methanation problem has been found, i.e., the graphitization of carbon supports at high temperatures (up to 2000°C) and the introduction of ruthenium promoters, specifically alkali (Cs, K) and alkali-earth (Ba) oxides, whose role is to modify the electron state of ruthenium and block the surface of a carbon support to prevent it from interacting with active hydrogen. The most efficient catalyst not liable to methanation up to 700°C and a hydrogen pressure of 100 atm has been found. The resulting analysis can be useful in selecting and preparing Me/C catalysts in which Me represents metals of the VIII Group and others. [ABSTRACT FROM AUTHOR]

The applicability of a porous carbon material obtained as a result of the 'chemical' dehydrochlorination of chlorinated polyvinyl chloride as a support for palladium hydrogenation catalysts was demonstrated. The efficiency of the catalyst was evaluated in the liquid-phase reactions of nitrobenzene hydrogenation and chlorobenzene hydrodechlorination. Although the specific activity of the catalyst was lower by a factor of 3-4 than that of the samples based on Sibunit and carbon nanotubes, the complete conversion of the initial compounds with the selective formation of end products under mild conditions was achieved at a relatively low palladium content (1.5%). [ABSTRACT FROM AUTHOR]

This work focuses on the catalytic activity and surface modification of Vulcan XC 72R and Printex L6 toward the oxygen reduction reaction (ORR) after the carbon supports were subjected to a pre-treatment with nitric acid or ammonia. The results indicated that acid-treated Printex L6 was the best-suited material toward the two-electron pathway of the ORR. This material contained the largest concentration of oxygenated acid species and hydrogen, as determined by XPS, the Boehm method, and elemental analysis. The enhanced formation of HO for acid-treated Printex L6 can be explained by the presence of oxygenated acid species increasing the hydrophilic character of the carbon support. The hydrophilicity of the material was investigated by contact angle measurements. However, the changes of the surface area, porosity, and the aliphatic chains of the carbons induced by the pre-treatments and the contributions of these factors to HO production cannot be disregarded. [ABSTRACT FROM AUTHOR]

The influence of different surface modifications of carbon supports on the corrosion resistance of 50 wt % Pt/C catalysts on their basis was studied. The corrosion resistance was measured from changes in the electroactive surface area of platinum in the course of potential cycling from 1.0 to 1.5 V versus the reversible hydrogen electrode (potential sweep rate, 0.5 V/s) during 60000 cycles. A 40% Pt/Vulcan XC-72 commercial catalyst was used as the reference sample. The supports were modified by the carbonization of the high surface area carbon black Ketjenblack DJ-600 and by the additional activation of the carbon-carbon composite Sibunit-1562. It was found that the preliminary carbonization of the Ketjenblack DJ-600 support with a propane-butane mixture at 770°C and the activation of Sibunit-1562 with subsequent thermal treatment at 500°C increased and decreased, respectively, the corrosion resistance of the 50 wt % Pt/C catalysts on their basis. [ABSTRACT FROM AUTHOR]

An efficient method was proposed for preparing supported platinum nanoparticles on the graphite by the deposition of Pt(0) binuclear clusters. The one-step method serves to promptly deposite Pt particles with a uniform morphology avoiding the use of additional reagents, such as reducing agents and stabilizers, which can be sorbed by carbon supports to contaminate the catalysts. Electron microscopy revealed an average size of platinum nanoparticles of 3-4 nm and a narrow particle-size distribution. [ABSTRACT FROM AUTHOR]

In the series of studied Pd/C catalysts, the highest selectivity for benzyl alcohol formation with complete conversion of benzaldehyde was demonstrated by the sample containing 1% palladium supported on carbon nanotubes when the reaction was carried out at 40 °C and 0.5 MPa. The 0.3% Pd/C catalysts have low activity. Increasing the palladium content and raising the reaction temperature leads to an increase in the toluene fraction in the reaction products. [ABSTRACT FROM AUTHOR]

New catalysts for the ammonia synthesis from dinitrogen and dihydrogen based on supported mononuclear potassium carbonyl ruthenate KRu[(CO)] as a precursor of catalytically active particles have been developed. Magnesium oxide and graphite-like active carbon Sibunit were used as supports, while aliphatic organolithium compounds (BuLi and BuLi) were employed as electron promoters in these catalysts. The systems with MgO as a support are the most efficient. The introduction of RLi into these systems allows one to considerably increase the ammonia synthesis rate. When using carbon Sibunit, the promoting effect of organolithium compounds is much weaker but the activity of such catalysts can be essentially increased by the introduction of an additional electron promoter, viz., metallic potassium, into the system. All the catalysts tested are active in the ammonia synthesis at atmospheric pressure and temperatures ≥250 °C. [ABSTRACT FROM AUTHOR]

Pt/carbon black samples fabricated from dimethyl (1,5-cyclooctadiene) platinum(II) in supercritical CO are characterized in relation to possible applications in methanol fuel cell. The problem of precise material characterization is addressed in frames of X-ray diffractometry, transmission electron microscopy, and electrochemical techniques of the true surface area determination. The catalysts with Pt loading of 20-40 wt.% consist of nm-size particles, with the lattice defectiveness dependent on the fabrication mode. To check the effect of support, various types of carbon blacks (Vulcan XC72R and acetylene black AC-1) are used. In contrast to commercial HiSpec catalysts, no pronounced increase of particle size with Pt loading is found. Specific steady-state activity towards methanol oxidation appears to be essentially higher than for commercial catalysts, mostly because the self-poisoning effects are less pronounced. As for poisoning of Pt with organic species (resulting from the ligand of precursor), its effects are demonstrated to be minor after CO or methanol adsorption accompanied by desorption of contaminating by-product. [ABSTRACT FROM AUTHOR]

The effect of fluorination on carbon blacks (CBs) was investigated by analyzing the CB surface functional groups. Also, fluorinated CB supported platinum–ruthenium electrocatalysts were studied. The surface characteristics of the fluorinated CB-supported catalysts were determined by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS), and their crystallinity was evaluated using X-ray diffraction (XRD). The electrochemical properties of the fluorinated CB-supported platinum and ruthenium (Pt/Ru CBs) catalysts were analyzed by cyclic voltammetry (CV). From the FT-IR results, the introduction of a fluorine atom onto CBs was confirmed by the existence of a carbon–fluorine (C–F) characteristic peak. The XPS result also showed that the fluorine content increased with increasing heat treatment temperature. The XRD analysis revealed that the catalysts are composed of mostly Pt and Ru. This result agreed with the fact that the electrochemical activity of the Pt/Ru CB catalysts was enhanced due to the small size and a high loading of catalysts by surface modification of the CBs. [ABSTRACT FROM AUTHOR]

Electrodeposition of Pt nanoparticles under potentiostatic conditions was performed on several types of carbon electrode supports: commercial macroporous carbon (a three-dimensional electrode), glassy carbon and graphite. Conducting polymers (poly-aniline and poly- o-aminophenol) were also used. The platinum nanoparticles were obtained by different Potential Step Deposition (PSD) methods in 5 mM H2PtCl6 + 0.5 M H2SO4 aqueous solutions. The effect of the final potential, time and number of steps on the quantity, distribution and size of the platinum nanoparticles was analysed. The mechanism of the electrochemical deposition of platinum was studied through the application of theoretical modelling. The progressive nucleation mechanism provided the closest agreement with the results obtained. In addition, the chemical state and morphology of the electrodeposited materials were determined by means of SEM, TEM and XPS. The results show that the carbon material structure has a strong influence on the Pt particle structure and this, in turn, affects the catalytic activity. [ABSTRACT FROM AUTHOR]

Pt/C electrocatalysts were prepared from a solution of H2PtCl6 in ethylene glycol in the presence of XC-72 carbon by adding a small amount of sodium acetate as stabilizer. Repeated TEM images showed that the platinum nanoparticles were small and uniform in size and highly dispersed on XC-72 carbon supports when a small amount of sodium acetate solution was added to the synthesis solution. The Pt/C electrocatalysts exhibited very high electrocatalytic activity for liquid methanol oxidation. The effects of adding acetate on Pt particle size and size distribution are discussed. It is demonstrated that acetate can be used as a good stabilizer for preparing Pt/C catalyst with fine and uniform Pt particles. [ABSTRACT FROM AUTHOR]

Approaches to control selectivity and activity in the catalytic reductive amination of butyraldehyde with ammonia over carbon supported noble metal catalysts (Ru, Rh, Pd, and Pt) were explored. Detailed analysis of the reaction network shows that the Schiff base N-[butylidene]butan-1-amine is the most prominent initial product and, only after nearly all butyraldehyde had been converted to N-[butylidene]butan-1-amine, amines are detected in the product mixture. From this intermediate, good hydrogenolysis catalysts (Ru, Rh) produce mostly butylamine, while catalysts less active in hydrogenolysis (Pd, Pt) lead to the hydrogenation of N-[butylidene]butan-1-amine to mostly dibutylamine. [ABSTRACT FROM AUTHOR]

Iron(III) tetramethoxyphenylporphyrins (FeTMPP-C1) adsorbed on high-area carbons were heat treated in an inert atmosphere at various temperatures ranging from 200–1000 °C to produce catalyst for the electroreduction of oxygen in acid electrolytes. It was found that the specific surface area of the FeTMPP-C1/C catalysts linearly decreases with increase of the FeTMPP-C1 loading on RB carbon. The electrical resistivity of the catalyst decreases with the increase of heat treatment temperature in the range of 200 to 800 °C, then it increases beyond 800 °C. The results obtained with elemental analysis, FTIR spectroscopy and XPS techniques indicate that the onset temperature for partial decomposition for the FeTMPP chelate occurs at temperatures of about 400–500 °C. The surface concentrations of both iron and nitrogen on the carbon support increase as the heat treatment temperature increases, and the maximum occurs at 700 °C. Some possibilities about the nature of active sites in the catalyst are discussed. [ABSTRACT FROM AUTHOR]