Fabrication of graphene-supported tetraferrocenylporphyrin electrocatalyst for oxygen reduction and its unique electrochemical response in both alkaline and acid media

A novel high-performance non-noble metal electrocatalyst for the oxygen reduction reaction (ORR) was fabricated by anchoring cobalt tetraferrocenylporphyrin (CoFcP) onto poly(sodium-p-styrenesulfonate) modified graphene (PSS-Gr) through solvothermally assisted π–π assembling method. The morphology of the assembled composite was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The interactions between CoFcP moieties and graphene sheets were confirmed by UV–Vis absorption spectroscopy and X-ray photoelectron spectroscopy. The electrocatalytic properties of the CoFcP/PSS-Gr catalyst towards the oxygen reduction reaction were assessed using rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) measurements in both alkaline and acidic media. In addition, cyclic voltammetry and chronoamperometric measurements were utilized to evaluate the catalytic activity and stability of the CoFcP/PSS-Gr composite in alkaline solution. The results showed that CoFcP supported on graphene exhibited an outstanding electrocatalytic performance towards the ORR comparable with commercial Pt/C catalyst in alkaline media, such as high onset potential (0.889 V vs. reversible hydrogen electrode, RHE), half wave potential (0.789 V vs. RHE), better tolerance to methanol, excellent stability (84.1 %, retention after 10000 s), and efficient four-electron pathway. Moreover, the proposed hybrid presented excellent catalytic activity in terms of onset potential (0.72 V vs. RHE) and high-electron transfer number compared with Pt/C in acidic media.     

B,N Co-Doped Three-Dimensional Carbon Aerogels with Excellent Electrochemical Performance for the Oxygen Reduction Reaction

Herein, an ordinary and mass-production approach is reported to synthesize boron (B) and nitrogen (N) co-doped three-dimensional (3D) carbon aerogels (CA) by using glucose and borax as the raw materials by a simple hydrothermal method and then carbonization in NH₃ atmosphere. The porous material (BN-CA-900) possesses a large specific surface area (1032 m² g⁻¹) and high contents of doped pyridinic N and graphitic N. The onset potential (0.91 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.77 V vs. RHE), and current density (5.70 mA cm⁻² at 0.2 V vs. RHE) of BN-CA-900 for ORR are similar to those of commercial Pt/C, indicating that BN-CA-900 has a comparable catalytic activity with Pt/C in alkaline media. The number of electron transfer is 3.86–3.99 and the yield of hydrogen peroxide is less than 6.8 %. BN-CA-900 also presents decent catalytic performance in acidic medium. Moreover, the stability and methanol tolerance of BN-CA-900 are superior to commercial Pt/C in both alkaline and acidic media. The prepared BN-CA-900 is a promising candidate that may be applied in other areas, such as the adsorption of pollution, porous conductive electrodes, and lithium-ion batteries.     

Ho3＋对吸附CO电化学氧化的促进作用

研究了吸附在Pt/C催化剂上的Ho3＋对吸附CO的电氧化的影响.结果表明,无论在中性和酸性溶液中,在较大的温度范围内,Ho3＋对CO在Pt/C催化剂上的电氧化都有促进作用,其原因是吸附Ho3＋的存在减弱了CO在Pt/C催化剂上的吸附强度.其次,在中性溶液中,Ho3＋对吸附CO的电氧化的促进作用比在酸性溶液中大.第三,无论在酸性还是中性溶液中,温度的升高有利于发挥Ho3＋对吸附CO的电氧化的促进作用.     

负载酞菁铁的氮掺杂中空碳球的电催化氧还原性能（英文）

开发低成本、高性能的氧还原反应（ORR）催化剂是当前的研究热点.虽然酞菁铁（FePc）在几十年前就被证明能高效地电催化氧还原反应,但由于其电子传导性和稳定性较差,无法取代商用的Pt/C催化剂.氮掺杂碳材料不仅化学性质稳定、电子传导性好,还有一定的氧还原催化活性.本文首先制备了聚苯乙烯@聚多巴胺球前驱体,经过高温碳化后制得了氮掺杂中空碳球,进而负载酞菁铁后制备了负载酞菁铁的氮掺杂中空碳球复合材料（FePc-NHCS）.通过调整煅烧温度和酞菁铁的负载量,可进一步调控FePc-NHCS的多孔结构、石墨化程度、氮掺杂的种类与含量及酞菁铁的负载状态.优化后的FePc-NHCS在碱性电解质中显示出优异的ORR催化活性,其半波电位和稳定性均高于商用Pt/C催化剂.研究结果表明,掺杂与复合是增强单项催化组分活性的有效途径.此外,通过调控催化剂的结构和组分也能有效地优化催化剂的氧化还原性能.     

Atomically Dispersed FeN2P2 Motif with High Activity and Stability for Oxygen Reduction Reaction Over the Entire pH Range

The past decade has witnessed the great potential of Fe-based single-atom electrocatalysis in catalyzing oxygen reduction reaction (ORR). However, it remains a grand challenge to substantially improve their intrinsic activity and long-term stability in acidic electrolytes. Herein, we report a facile chemical vapor deposition strategy, by which high-density Fe atoms (3.97 wt%) are coordinated with square-planar para-positioned nitrogen and phosphorus atoms in a hierarchical carbon framework. The as-crafted atomically dispersed Fe catalyst (denoted Fe-SA/PNC) manifests an outstanding activity towards ORR over the entire pH range. Specifically, the half-wave potential of 0.92 V, 0.83 V, and 0.86 V vs. reversible hydrogen electrode (RHE) are attained in alkaline, neutral, and acidic electrolytes, respectively, representing the high performance among reported catalysts to date. Furthermore, after 30,000 durability cycles, the Fe-SA/PNC remains to be stable with no visible performance decay when tested in 0.1 M KOH and 0.5 M H₂SO₄, and only a minor negative shift of 40 mV detected in 0.1 M HClO₄, significantly outperforming commercial Pt/C counterpart. The coordination motif of Fe-SA/PNC is validated by density functional theory (DFT) calculations. This work provides atomic-level insight into improving the activity and stability of non-noble metal ORR catalysts, opening up an avenue to craft the desired single-atom electrocatalysts.     

Amino-metalloporphyrin polymers derived Fe single atom catalysts for highly efficient oxygen reduction reaction

Recently, nitrogen-doped porous carbon supported single atom catalysts(SACs) have become one of the most promising alternatives to precious metal catalysts in oxygen reduction reaction(ORR) due to their outstanding performance, especially those derived from porphyrin-based materials. However, most of them involve other metal residuals, which would cause the tedious pre-and/or post-treatment, even mislead the mechanistic investigations and active-site identification. Herein, we report a precursor-dilution strategy to synthesize Fe SACs through the Schiff-based reaction via co-polycondensation of amino-metalloporphyrin, followed by pyrolysis at high temperature. Systematic characterization results provide the compelling evidence of the dominant presence of atomically dispersed Fe-Nxspecies. Our catalyst shows superior ORR performance with positive half-wave potential(E_(1/2)=0.85 V vs. RHE) in alkaline condition and moderate activity(E_(1/2)=0.68 V vs. RHE) under the acidic condition, excellent methanol tolerance and good long-term stability. All the results indicate Fe SACs would be a promising candidate for replacing the precious Pt in metal-air batteries and fuel cells.     

Spontaneous Bi-modification of polycrystalline Pt electrode: fabrication, characterization, and performance in formic acid electrooxidation

Spontaneous modification of polycrystalline Pt by irreversibly adsorbed bismuth was performed in BiCl₃ solution in concentrated hydrochloric acid under open-circuit conditions. After spontaneous modification, followed by extensive rinsing with water and drying, the surface was characterized using X-ray photoelectron spectroscopy and electrochemistry. Bi-oxy(chloride), oxide species, and metallic Bi were found at a submonolayer coverage on the Pt surface after spontaneous modification. The electrochemical response of Bi-modified polycrystalline Pt electrode in sulfuric acid solution exhibits a complex multi-peak feature, which is resulting in about constant redox charge (Bi species coverage) in the potential region from 0 to 0.9 V (vs. a standard hydrogen electrode). The spontaneously Bi-modified Pt catalyst in model studies exhibits a superior activity towards formic acid oxidation at fuel cell anode relevant potentials. The catalytic effect of bismuth oxy-species is explained in terms of both inhibition of CO_ad formation and oxidation of CO_ad in reaction with Bi-oxy-species.     

Fe/Fe3C Nanoparticles Encapsulated in N-Doped Hollow Carbon Spheres as Efficient Electrocatalysts for the Oxygen Reduction Reaction over a Wide pH Range

Nonprecious-metal-based electrocatalysts with low cost, high activity, and stability are considered as one of the most promising alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR). Herein, an economical and easy-to-fabricate catalyst is developed, that is, Fe/Fe₃C embedded in N-doped hollow carbon spheres (Fe/Fe₃C/NHCS), which gave the half-wave potential of 0.84 V in 0.1 m KOH, similar to the commercial Pt/C catalyst. Surprisingly, the favorable ORR performance of the as-prepared catalyst was obtained in both acidic and neutral conditions with almost a four-electron pathway and low H₂O₂ yield, which desirable the development of the proton exchange membrane (PEM) and microbial electrolysis cell (MEC) technology. Additionally, the obtained catalyst demonstrated better long-term stability and high methanol tolerance over a wide range of pH. These features could be mainly attributed to the synergistic effect between Fe/Fe₃C and Fe-N_x sites, the hollow structure with mesopores, and the well-dispersed Fe/Fe₃C nanoparticles owing to the existence of the abundant hydrophilic groups within the HCS precursor. As such, designing an efficient and cheap ORR catalyst that can operate at alkaline, acidic, and neutral solutions is highly desirable, yet challenging.     

Potential‐Cycling Synthesis of Single Platinum Atoms for Efficient Hydrogen Evolution in Neutral Media

Single‐atom catalysts (SACs) have exhibited high activities for the hydrogen evolution reaction (HER) electrocatalysis in acidic or alkaline media, when they are used with binders on cathodes. However, to date, no SACs have been reported for the HER electrocatalysis in neutral media. We demonstrate a potential‐cycling method to synthesize a catalyst comprising single Pt atoms on CoP‐based nanotube arrays supported by a Ni foam, termed PtSA‐NT‐NF. This binder‐free catalyst is centimeter‐scale and scalable. It is directly used as HER cathodes, whose performances at low and high current densities in phosphate buffer solutions (pH 7.2) are comparable to and better than, respectively, those of commercial Pt/C. The Pt mass activity of PtSA‐NT‐NF is 4 times of that of Pt/C, and its electrocatalytic stability is also better than that of Pt/C. This work provides a large‐scale production strategy for binder‐free Pt SAC electrodes for efficient HER in neutral media.     

Platinum nanoparticles supported on nitrobenzene-functionalised graphene nanosheets as electrocatalysts for oxygen reduction reaction in alkaline media

A systematic study on the electrocatalytic properties of Pt nanoparticles supported on nitrobenzene-modified graphene (Pt-NB/G) as catalyst for oxygen reduction reaction (ORR) in alkaline solution was performed. Graphene nanosheets were spontaneously grafted with nitrophenyl groups using 4-nitrobenzenediazonium salt. The electrocatalytic activity towards the ORR and stability of the prepared catalysts in 0.1 M KOH solution have been studied and compared with that of the commercial Pt/C catalyst. The results obtained show that the NB-modified graphene nanosheets can be good Pt catalyst support with high stability and excellent electrocatalytic properties. The specific activity of Pt-NB/G for O₂ reduction was 0.184 mA cm⁻², which is very close to that obtained for commercial 20 wt% Pt/C catalyst (0.214 mA cm⁻²) at 0.9 V vs. RHE. The Pt-NB/G hybrid material promotes a four-electron reduction of oxygen and can be used as a promising cathode catalyst in alkaline fuel cells.     

Highly Active Electrocatalyst Derived from ZIF-8 Decorated with Iron(III) and Cobalt(III) Porphyrin Toward Efficient Oxygen Reduction in Both Alkaline and Acidic Media

Zeolite imidazole frameworks 8(ZIF-8) and modified ones after pyrolysis are highly promising toward oxygen reduction reaction(ORR). Especially, the compositional modification of ZIF-8 is crucial to the enhancement of ORR performance, yet limited to the substitution of skeletal Zn(II) with other cations or simple physical adsorption of cations. Herein, we report the decoration of ZIF-8 with ORR active hemin(FeP) and Co(III) protoporphyrin(CoP) via the coordination between the peripheral carboxylic group of FeP and CoP with skeletal Zn(II). This allows well control over the quantity of loaded FeP and CoP, critical to the synthesis of advanced electrocatalysts. Subsequent pyrolysis of FeP and CoP co-decorated ZIF-8 leads to highly active ORR electrocatalysts with a half-wave potential(E_1/2) of 0. 913 V(vs. RHE) in 0.1 mol/L KOH aq. and an E_1/2 of 0.803 V(vs. RHE) in 0.1 mol/L HClO₄ aq. Moreover, our electrocatalyst shows much more improved and comparable durability in alkaline and acidic media, respectively, during 3000 cycles of cyclic voltammetry(CV) scanning relative to commercial Pt/C.     

Nanosheets with High-Performance Electrochemical Oxygen Reduction Reaction Revived from Green Walnut Peel

The synthesis of metal-free carbon-based electrocatalysts for oxygen reduction reactions (ORR) to replace conventional Pt-based catalysts has become a hot spot in current research. This work proposes an activation-assisted carbonization strategy, to manufacture N-doped ultra-thin carbon nanosheets (GWS180M800) with high catalytic activity, namely, melamine is used as an accelerator/nitrogen source, and walnut green peels biological waste as a carbon source. The melamine acts as a nitrogen donor in the hydrothermal process, effectively enhancing the nitrogen doping rate. The content of pyridine nitrogen groups accounts for up to 48.5% of the total nitrogen content. Electrochemical tests show that the GWS180M800 has excellent ORR electrocatalytic activity and stability, and makes a quasi-four-electron ORR pathway clear in the alkaline electrolyte. The initial potential and half slope potential are as high as 1.01 and 0.82 V vs. RHE, respectively. The GWS180M800 catalyst has a better ability to avoid methanol cross poisoning than Pt/C has. Compared with 20 wt% Pt/C, GWS180M800 has improved methanol tolerance and stability. It is a metal-free biochar ORR catalyst with great development potential and application prospects. This result provides a new space for the preparation of valuable porous nano-carbon materials based on carbonaceous solid waste and provides new ideas for catalyzing a wide range of electrochemical reactions in the future.     

Nitrogen‐Doped Carbon Nanosheets with Size‐Defined Mesopores as Highly Efficient Metal‐Free Catalyst for the Oxygen Reduction Reaction

Nitrogen‐doped carbon nanosheets (NDCN) with size‐defined mesopores are reported as highly efficient metal‐free catalyst for the oxygen reduction reaction (ORR). A uniform and tunable mesoporous structure of NDCN is prepared using a templating approach. Such controlled mesoporous structure in the NDCN exerts an essential influence on the electrocatalytic performance in both alkaline and acidic media for the ORR. The NDCN catalyst with a pore diameter of 22 nm exhibits a more positive ORR onset potential than that of Pt/C (?0.01 V vs. ?0.02 V) and a high diffusion‐limited current approaching that of Pt/C (5.45 vs. 5.78 mA cm^?2) in alkaline medium. Moreover, the catalyst shows pronounced electrocatalytic activity and long‐term stability towards the ORR under acidic conditions. The unique planar mesoporous shells of the NDCN provide exposed highly electroactive and stable catalytic sites, which boost the electrocatalytic activity of metal‐free NDCN catalyst.     

Synergistic Enhancement of Electrocatalytic Activity toward Oxygen Reduction Reaction in Alkaline Electrolytes with Pentabasic (Fe,B, N,S, P)‐Doped Reduced Graphene Oxide

As alternatives to Pt‐based electrocatalysts, the development of nonprecious metal catalysts with high performance in the cathodic oxygen reduction reaction (ORR) is highly desirable for widespread use in fuel cells. Here we report a simple approach for preparing pentabasic (Fe, B, N, S, P)‐doped reduced graphene oxide (rGO) via a two‐step doping method of adding boric acid and ferric chloride to ternary (N, S, P)‐doped rGO (NSPG). Electrochemical investigation of the composites for the ORR revealed that simultaneously doping appropriate amounts of Fe and B into the NSPG produced a synergistic effect that endowed the prepared catalyst with both a positively shifted ORR half‐wave potential and high selectivity for the 4e^? reduction of O₂. The optimized Fe₂B‐NSPG catalyst approached a 4e^? process for the ORR with a half‐wave potential (E_1/2=0.90 V vs. RHE) even 30 mV higher than that of the commercial Pt/C catalyst in alkaline solution. Furthermore, relative to the Pt/C catalyst, the Fe₂B‐NSPG demonstrated superior stability and excellent tolerance of the methanol cross‐over effect. This simple method afforded pentabasic (Fe, B, N, S, P)‐doped rGO as a promising nonprecious metal catalyst used for alkaline fuel cells.     

Kinetic studies of adsorbed CO electrochemical oxidation on Pt(335) at full and sub-saturation coverages

Electrochemical measurements were performed to characterize the kinetics of adsorbed CO oxidation on the surface of the stepped Pt(s)-[4(111)x(100)][triple bond, length half m-dash]Pt(335) single crystal electrode. For CO adsorbed to full coverage at 0.1 V (versus the reversible hydrogen electrode, RHE) in 0.5 M H(2)SO(4) at ambient temperature (23 degrees C), oxidation of the layer gave 7.6 x 10(14) +/- 0.3 CO/cm(2) as the saturation CO coverage, just below the average value reported for CO on Pt(335) in ultra high vacuum (8.3 x 10(14) +/- 0.6 CO/cm(2)). In potential step measurements carried out between 0.75 and 0.9 V, the peak region in the current-time transient was consistent with the surface reaction between adsorbed CO and adsorbed oxide as rate limiting. Plotting the log of the rate constant for the surface reaction versus potential gave a Tafel slope of 79 mV per decade, consistent with responses for CO electrochemical oxidation on structurally related stepped Pt electrodes. For CO coverages below saturation, current-time transients were more stable in 0.05 M H(2)SO(4) than in the higher concentration electrolyte. Numerically solving the rate equations to the Langmuir-Hinshelwood model of adsorbed CO electrochemical oxidation reproduced the main features in current-time transients measured at 0.7 V in 0.05 M H(2)SO(4) for sub-saturation CO coverages. The results provide new insights into CO oxidation on Pt at sub-saturation coverage and confirm that anions play a role in CO surface chemistry.     

Tungsten carbide nanocrystal promoted Pt/C electrocatalysts for oxygen reduction

Tungsten carbide nanocrystals on carbon (W2C/C) and tungsten carbide nanocrystals and Pt on carbon (Pt-W2C/C) composite electrocatalysts were prepared by the intermittent microwave heating (IMH) method and tested for the electroreduction of oxygen in the acidic media for the first time. The results revealed that the tungsten carbide nanocrystal promoted Pt/C electrocatalyst was very active for ORR with the onset potential of 1.0 V vs SHE at ambient temperature that is over 100 mV more positive compared with that of traditional Pt/C electrocatalyst. The kinetic parameters were determined. The exchange current densities at both high and low overpotential regions are two orders higher for ORR on Pt-W2C/C than that on Pt/C, showing a synergetic effect to improve the activity for ORR. The novel electrocatalysts show a poisoning resistant property toward methanol.     

纳米颗粒结合ZIF-67衍生的PtCo-NC催化剂用于醇类燃料电氧化

Alcohols fuel electro-oxidation is significant to the development of direct alcohols fuel cells, that are considered as a promising power source for portable electronic devices. Currently, the catalyst was restricted by the serious poisoning effect and high cost of noble metals. Developing low-cost Pt alloy with high performance and anti-CO poisoning ability was highly desired. In this work, PtCo-NC catalyst was synthesized by combining Pt nanoparticles with ZIF-67 after annealing in the tube furnace and the in situ generated N-doped carbon from ZIF-67 was functionalized to support the PtCo alloy nanoparticle. The structure and morphology were probed by X-ray diffraction, scanning electron microscope and transmission electron microscope, and the electrochemical performance was evaluated for alcohols of methanol and ethanol oxidation in the acid electrolyte. Compared with the reference sample of Pt/C, several times performance enhancement for alcohols fuel oxidation was found on PtCo-NC catalyst as well as the good catalytic stability. Specifically, the peak current density of PtCo-NC was 79.61 mA∙cm⁻² for methanol oxidation, about 2.2 times higher than that of the Pt/C electrode (36.97 mA∙cm⁻²) and 2.5 times higher than that of the commercial Pt/C electrode (31.23 mA∙cm⁻²); it was 62.69 mA∙cm^–2 for ethanol oxidation, about 1.65 times higher than that of Pt/C catalyst (37.99 mA∙cm⁻²) and commercial Pt/C electrode (37.77 mA∙cm⁻²). These catalytic performances were also much higher than some analogous catalysts developed for alcohols fuel oxidation. A much higher anti-CO poisoning ability was demonstrated by the CO stripping voltammetry experiment, in which the CO_ad oxidation peak potential for PtCo-NC was 0.46 V, ca. 110 mV negative shift compared with Pt/C catalyst at 0.57 V. A strong electronic effect was indicated by the peak position shifting to the lower binding energy direction by 0.3 eV on PtCo-NC compared with Pt/C reference catalyst. According to the d-band center theory, the electron-enriched state of Pt will decrease the interaction strength of poisoning intermediates adsorbed on its surface; Moreover, according to the bifunctional catalytic mechanism, the presence of Co can form the adsorbed oxygen-containing species (―OH) more easily than Pt at low potentials, and this oxygen-species were helpful in the oxidation of CO_ad at neighboring Pt sites. The high catalytic performance for alcohols fuel oxidation could be due to the largely improved anti-CO poisoning ability and the synergistic effect between the in situ formed PtCo nanoparticles and the N-doped carbon support.     

A promising amendment for water splitters: Boosted oxygen evolution at a platinum,titanium oxide and manganese oxide hybrid catalyst

A hybrid catalyst composed of a platinum thin layer and modified with manganese oxide (MnOx) is recommended for the oxygen evolution reaction (OER). The Pt layer of the catalyst was physically sputtered onto a TiOx-coated Si substrate (this TiOx layer was sputtered inbetween the Si substrate and Pt layer to improve their adhesion and prevent their mutual diffusion). On top of the Pt layer, another thin TiOx layer (∼60 nm) was spun before the electrochemical deposition of MnOx. The investigation focused primarily to evaluate the impact of the catalyst’s annealing in oxygen atmosphere on its catalytic activity toward OER. Interestingly, before the modification with MnOx, a large catalytic enhancement both in activity (∼228 mV negative shift at 20 mA cm⁻² if compared to conventional bare Pt catalysts) and stability was achieved at the catalyst annealed at 600 °C toward OER in 0.5 M KOH. Surprisingly, the addition of MnOx to the catalyst synergized a boosted activity amplifying the negative shift to 470 mV at the same current density. Bunch of materials and electrochemical techniques were combined to reveal important remarks about the catalyst’s morphology, structure, composition and intrinsic activity which was attributed to electronic rather than geometric factors.     

A spin-coated TiOx/Pt nanolayered anodic catalyst for the direct formic acid fuel cells

The CO poisoning of the platinum anodic catalyst which typically functions the catalytic deterioration of the direct formic acid fuel cells could be minimized with a simple modification for Pt with titanium oxide. The fabrication scheme involved the spin-coating of a Ti precursor onto a Pt thin layer that was physically sputtered onto a Si substrate. The whole assembly was subjected to a post-annealing processing to produce the TiOx layer (60 nm) in a porous structure (mostly Anatase) atop of the Pt surface. The porous nature of the TiOx layer permitted the participation of Pt in the electrocatalysis of the formic acid electro–oxidation (FAO). The annealing temperature was critical in identifying the catalytic efficiency and durability of the catalyst toward the FAO. Interestingly, if compared to bare-Pt substrates, the TiOx-modified catalysts could successfully steer the FAO toward the direct dehydrogenation (favorable and less energetic) pathway with more than an order of magnitude increase in the catalytic activity. It also provided a great opportunity for the mitigation of poisoning CO; concurrently with a lowering (~0.3 V) in the onset potential of the FAO. The scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction spectroscopy (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were all combined to evaluate, respectively, the catalyst’s morphology, composition, crystal structure and activity and further to understand the role of the TiOx in the catalytic enhancement.     

Electronic Effect of Carbon Support on Pt Catalyst Supported on Graphite Intercalation Compound

Graphite intercalation compounds(GIC) were tested as an experimental model for studying the electronic effect of carbon support on the catalytic activity and poisoning tolerance of Pt catalyst for direct methanol fuel cells. The GIC samples with different intercalation degrees were prepared by electrolyzing graphite flake in H2SO4 for varying the periods of time. The GIC-supported Pt catalyst was deposited electrochemically. The catalytic activity and poisoning tolerance of the GIC-supported Pt catalysts were evaluated. It was found that GIC with sulfate anion as intercalate was able to catalyze methanol electrooxidation, which could be related to the positive charges generated on the graphite layer upon intercalation. As intercalation degree increased, the catalytic activity of the GIC-supported Pt catalyst decreased while the poisoning tolerance improved. This suggests that electron donation from support to catalyst had great effect on both catalytic activity and poisoning tolerance of Pt catalyst. And intercalation can be adopted as another important way to make modification on carboneous catalyst support.