Activity For Formic Acid Electrooxidation Research Articles

Carbon layer thickness manipulated polarized electric field on palladium for formic acid electrooxidation

To solve the severe problem of environmental pollution, the demand for commercial applications of direct formic acid fuel cell (DFAFC) has significantly increased. Designing electrocatalysts with high anti-poisoning ability and activity for formic acid electrooxidation (FAO) is the key for the development of DFAFC. Utilizing polarized electric field is a new attempt to improve catalytic performance as it can adjust the adsorption energy of reactants or intermediate species on the catalysts. In this work, pyroelectric material BaTiO3 (BTOH), which generate polarized electric field, was introduced for FAO for the first time. A series of core–shell structured Pd/BTOHx@NCy catalysts was synthesized with BTOH as the core, nitrogen-doped carbon as the shell, and palladium nanoparticles as the active sites. Among all catalysts, Pd/BTOH1@NC0.5 with the optimal carbon shell thickness of 4.6 nm owns the highest FAO catalytic activity and anti-poisoning ability because the carbon layer regulates the electric field strength to optimize the palladium surface adsorption energy. The study excluded the influence of electronic effect and revealed the effect of polarized electric field strength on the FAO activity and anti-poisoning ability through changing the thickness of carbon shell. In addition, the alternating cold-hot excitation experiments demonstrated that the polarized electric fields can effectively remove the poisoned substance on the surface of palladium. This study guides a new strategy to design electrocatalysts for FAO.

Constructing poison-resistant Au-Pd single-atom alloy electrocatalyst on Pd nanocrystals for formic acid electrooxidation

Pd is a promising anodic catalyst for direct formic acid fuel cells, while its performance on formic acid electrooxidation is still suffered from for low catalytic efficiency and durability. In this work, an electrochemical self-catalyzed method was employed to deposit Au single-atoms onto Pd nanocrystals with tuneable compositions. Spherical-corrected Scanning transmission microscope and electrochemical characteristics demonstrated that the Au atoms were atomic-dispersive on Pd nanocrystals, forming Au-Pd single-atom alloy. Systematic studies showed that the activity of Pdx @Auy/C SAA is related to the density of the Au single-atoms on Pd surface. When an optimized balance between active-site exposure and intrinsic activity is achieved, the Pd50 @Au1/C SAA showed superb formic acid electrooxidation activity of 4.98 A mg−1M and unusual high anti-poisoning ability which is distinctly different from most of the Pd based catalysts. The boosted electrochemical performances of Pdx @Auy/C SAA can be attributed to the unique geometric effect that facilitates the direct reaction route and favourable electronic effect that weakens the CO adsorption to Pd sites.

Effect of MoO3 on Pd nanoparticles for efficient formic acid electrooxidation

Palladium is a promising formic acid electro-oxidation (FAO) catalyst due to its higher initial activity than platinum. However, suffering from the adsorption of hydrogen and CO-like species, the activity and stability of Pd are still unsatisfied. Herein, palladium nanoparticles deposited on carbon supported molybdenum trioxide (Pd–MoO3/C) is prepared with MoO3 as the promoter for FAO. X-ray photoelectron spectroscopy analysis proves the close contact between Pd and MoO3, which generates the hydrogen spillover effect and forms the Pd–Mo structure. The hydrogen spillover effect enhances the desorption of hydrogen from Pd and facilitates the FAO activity. Both the spillover effect and Pd–Mo structure contribute to the removal of COad and facilitate the durability and anti-CO poisoning ability of the catalyst. With the optimized ratio of MoO3 to carbon black, the Pd–MoO3/C-20 catalyst owns the best specific activity of 5.86 mA cm−2, which is 1.86 times of Pd/C.

Superior formic acid electrooxidation activity on carbon nanotube‐supported binary Pd nanocatalysts prepared via sequential sodium borohydride reduction technique

In this study, multiwalled carbon nanotube (MWCNT)‐supported M (Pd, Ni, Co, Mn, V, Zn)/MWCNT monometallic and M (Ni, Co, Zn, V, Ag, Mn)@(Pd/MWCNT) binary nanocatalysts were investigated to examine the effect of second metal promotion to Pd on formic acid electrooxidation (FAEO) activity. The sequential sodium borohydride (SBH) reduction technique was used for the preparation of nanocatalysts. For binary nanocatalysts, first of all, the monometallic Pd/MWCNT nanocatalyst was prepared. Then, second metal precursors (NiCI2, CoCl2, ZnCI2, V2O5, AgNO3, and MnCI2) were added to Pd/MWCNT and further reduced with NaBH4. After filtration and drying, binary nanocatalysts M@(Pd/MWCNT) were obtained. X‐ray diffractometry (XRD), inductively coupled plasma mass spectrometer (ICP‐MS), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS) methods were used to characterize the obtained nanocatalysts. In addition, cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements were utilized to examine the electrochemical activities of the nanocatalysts for FAEO. The results indicate that Ni@(Pd/MWCNT) nanocatalyst is better than the other nanocatalysts with 10.75‐mA cm−2 specific and 2924.48‐mA mg−1 Pd mass activity. Furthermore, Ni@(Pd/MWCNT) nanocatalyst has 110.4‐m2 g−1 electrochemical active surface area (ECSA). Consequently, it is clear that Ni@(Pd/MWCNT) nanocatalyst is a promising nanocatalyst for direct formic acid fuel cells (DFAFCs).

PdNi/N-doped graphene aerogel with over wide potential activity for formic acid electrooxidation

Anti-CO poisoning ability is significant in formic acid oxidation in the fuel cell technique. Herein, PdNi alloy supported on N-doped graphene aerogel (PdNi/GA-N) was found to have catalytic ability toward formic acid electrooxidation over a wide potential range because of the improved anti-CO poisoning ability. This catalyst was fabricated by simple freeze-drying of mixture solution of graphene aerogel, polyvinylpyrrolidone, Pd2+ and Ni2+ and the subsequent thermal annealing reduction approach in the N2/H2 atmosphere. Pd–Ni alloy particles anchored over the folding N-doped graphene surface with a porous hierarchical architecture structure in the 3D directions. It showed the catalytic performance of its maximum mass activity of 836 mA mg−1 in a broad potential range (0.2–0.6 V) for formic acid oxidation. The CO stripping experiment demonstrated its largely improved anti-CO poisoning ability with the peak potential of 0.67 V, approximately 60 and 40 mV less compared to those of Pd/GA-N and Pd/C samples. The high anti-CO poisoning ability and strong electronic effect resulting from the interaction between the 3D GA-N support and the Pd–Ni alloy makes it a promising catalyst for application in direct formic acid fuel cells.

Tungsten-induced synthesis of defective palladium–copper–tungsten trimetallic nanochains to highly enhance activity for formic acid electrooxidation

Great efforts have been devoted to the exploration of PdCu-based catalysts toward formic acid oxidation, but their activity is still much lower than that expected. In this work, nanotwin-rich PdCuW trimetallic nanochains were successfully fabricated using a modified polyol method. The formation of crystalline defect of nanotwins should be related to the significant lattice mismatch among Pd, Cu, and the introduced W. It is discovered that the nanotwins could function as superb active sites to highly improve the peak current density of formic acid oxidation. In addition, the W- and Cu-tailored PdCuW nanochains optimize the electronic structure of Pd with suitable binding energy to reduce the charge-transfer resistance, resulting in greatly enhanced catalytic activity. This work highlights the beauty of the architecture with introduced W to significantly enhance catalytic performance in particular the activity of formic acid electrooxidation.

Improving the electrocatalytic performance of Pd for formic acid electrooxidation by introducing tourmaline

Palladium is the most effective catalyst with high initial activity for formic acid electrooxidation (FAEO) in direct formic acid fuel cells (DFAFCs), but the low performance of DFAFC comparing to H2-PEMFC and the accumulation of COad poisoning species on palladium restrict the commercialization of DFAFC. Herein, a novel and efficient FAEO catalyst, tourmaline modified Pd (Pd/TNP@SC) are prepared. A class of core@shell structured carbon coated tourmaline (TNP@SC) are equipped as the catalyst support to efficiently utilize the spontaneous polarization-induced electric field and far-infrared radiation of tourmaline for FAEO reaction. Physical and electrochemical measurements suggest that the existence of electric field and far-infrared radiation of tourmaline promote synthesizing smaller Pd nanoparticles, weakening the Pd-O bond, increasing molecular vibration and migration rate, and dissociating water molecules into OHad to spontaneously convert COad into CO2. Even under potentials applied higher than 0.3 V (vs. Ag/AgCl), Pd/TNP@SC catalysts still have high FAEO activity. Among all the Pd/TNP@SC catalysts investigated in this study, Pd/TNP@SC-800 owns the strongest electric field and far-infrared radiation, exhibits the best activity for FAEO, which is 3.1 times higher than that of tourmaline-free catalyst (Pd/SC)), and excellent CO-tolerance during FAEO reaction. This work provides an effective catalyst design strategy for FAEO.

Tailoring the metallic composition of Pd, Pt, and Au containing novel trimetallic catalysts to achieve enhanced formic acid electrooxidation activity

Herein, carbon-supported Pt, PtAu, and PdPtAu catalysts were synthesized via the NaBH4 reduction method. Electrocatalytic activity of the catalysts for formic acid electrooxidation was investigated by using cyclic voltammetry (CV), chronoamperometry (CA), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). X-ray diffraction (XRD), N2 adsorption-desorption, and temperature programmed reduction (TPR) techniques were used for the characterization of the synthesized catalysts. The enhanced electrocatalytic activity was observed for PtAu catalysts by the addition of Pd which can be explained through the synergistic effect between Pd and Au. Pd75Pt5Au20/CNT exhibited the highest catalytic activity of 36.8 mAcm−2, and similar results were also obtained for other trimetallic catalysts containing low amount of Pt. These results lead us to conclude that low Pt content provides higher electrocatalytic activity and CO poisoning tolerance. To our knowledge, the significance of Pd ratio optimization for PdPtAu catalyst system was reported for the first time in the literature.

Effective carbon nanotube supported metal (M=Au, Ag, Co, Mn, Ni, V, Zn) core Pd shell bimetallic anode catalysts for formic acid fuel cells

At present, CNT supported Pd and core-shell Pd-based catalysts are synthesized by employing the NaBH4 reduction method to investigate on formic acid electrooxidation (FAEO) activity. These catalysts are characterized by XRD, TEM, HRTEM, and XPS. The XRD results display that the electronic state of catalysts changed by second metal addition to Pd. TEM results reveal that Au and Pd are homogeneously distributed. XPS results of AucorePdshell/CNT catalyst show that Au and Pd atoms used in the preparation of the catalyst are obtained mainly in elemental state. The FAEO activity, stability, and resistance of these catalysts are investigated by employing cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The CV results show that AucorePdshell/CNT catalyst having 16.42 mAcm−2 specific activity and 4978.23 mA mg−1 Pd mass activity is better than other catalysts. In addition, the AucorePdshell/CNT (21 m2/g) catalyst has better electrochemical active surface area (ECSA) value as 5.25 times compared with Pd/CNT catalyst. Direct formic acid fuel cell (DFAFC) performances are performed at different temperatures for AucorePdshell/CNT and NicorePdshell/CNT catalysts. The specific activity of AucorePdshell/CNT catalyst is 2.5 times higher than the value for NicorePdshell/CNT catalyst. AucorePdshell/CNT catalyst is a promising catalyst for DFAFCs.

Novel carbon nanotube supported Co@Ag@Pd formic acid electrooxidation catalysts prepared via sodium borohydride sequential reduction method

At present, monometallic Pd/CNT, bimetallic Pd50Ag50/CNT, Pd50Co50/CNT, Ag50Pd50/CNT catalysts are prepared by NaBH4 co-reduction method. Ag@Pd/CNT catalysts at varying Ag:Pd ratios and Co@Ag@Pd/CNT catalysts at varying Co:Ag:Pd atomic ratios are prepared via NaBH4 sequential reduction method. These catalysts are characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The characterization results show that all catalysts are successfully synthesized at desired molar composition. Furthermore, Ag and Co addition change electronic state of catalyst. Formic acid electrooxidation measurements of these catalysts are performed by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) to investigate the effect of Ag and Co addition through the formic acid electrooxidation activity. Considering the bimetallic catalysts, Ag20@Pd80/CNT exhibits better catalytic activity than the one of other bimetallic catalysts. It is clear that the addition of Ag to Pd improves electrocatalytic activity due to synergetic effects. Furthermore, Co0.072@Ag19.98@Pd79.98/CNT has the best activity, lowest charge transfer resistance (Rct), and a long term stability. EIS and CA results are in a good agreement with CV results. Co0.072@Ag19.98@Pd79.98/CNT is a promising catalyst for Direct formic acid fuel cells.

Synthesis and characterization of Co, Zn, Mn, V modified Pd formic acid fuel cell anode catalysts

In this study, carbon nanotube (CNT) supported Pd50Co50, Pd50V50, Pd50Mn50, and Pd50Zn50 bimetallic catalysts are prepared by using sodium borohydride (NaBH4) reduction method to investigate their formic acid electrooxidation (FAEO) activities. These catalysts are characterized by using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), and X-ray Photoelectron Spectroscopy (XPS). The XRD results show that the electronic state of catalysts varied by second metal addition to Pd. TEM results reveal that Pd and Co are homogeneously distributed. The result of Pd43Co57/CNT obtained by ICP-OES analysis of Pd50Co50/CNT catalyst shows that the synthesis was successfully synthesized. XPS results of Pd50Co50/CNT and Pd50Zn50/CNT catalysts showed that Pd, Zn, and Co atoms used in the preparation of the catalysts were obtained mainly in their elemental state. In addition, FAEO activity and stability of these catalysts are examined by using cyclic voltammetry (CV) and chronoamperometry (CA). Pd50Co50/CNT indicated the highest specific and mass activities with 6.89 mA/cm2 and 649.69 mA/mg Pd, respectively. Direct formic acid fuel cell (DFAFC) performances are performed in different temperatures for Pd50Co50/CNT catalyst. The specific current for DFAFC performance of this catalyst was evaluated as 5.71, 6.87, and 2.43 mA/cm2 at 18 °C, 30 °C, and 60 °C cell temperature at 0.5 V, respectively.

Carbon monoxide and formic acid electrooxidation study on Au decorated Pd catalysts prepared via microwave assisted polyol method

In this study, carbon supported Pd monometallic and PdAu bimetallic catalysts are prepared by using microwave assisted polyol method to investigate their carbon monoxide and formic acid electrooxidation activities. These catalysts are characterized by using Scanning Electron Micrsocopy (SEM-EDX) and N2 adsorption desorption measurements. EDX measurements reveal that catalysts are prepared at desired ratios. The electrochemical characterization was performed via cyclic voltammetry and CO stripping voltammetry. Electrochemical surface area (ECSA) was calculated thanks to CO oxidation peaks. It was reported that CO tolerance and ECSA of the PdAu/C catalysts were higher than that of the Pd/C, attributed to sweeping effect of Au particles in terms of CO adsorption. Furthermore, formic acid electrooxidation activity of these catalysts are examined by using cyclic voltammetry (CV). PdAu/CNT catalyst at prepared at 90:10 Pd:Au ratio exhibited the highest formic acid electroxidation activity. It is clear that PdAu/CNT catalyst is a promising catalyst for CO and formic acid electrooxidation.

Effects of preparation conditions on the morphology and performance of palladium nanostructures

Three-dimensional palladium nanoflowers (PdNF) composed of ultrathin Pd nanosheets had been synthesized by a solvothermal approach in our previous work. Here, the effects of preparation conditions on the morphology and electrochemical performance of palladium nanostructures were investigated. The explored conditions are as follows: the ratio of reducing agent to capping agent, the concentration of PdCl2 precursor, the amount of HCl (used for PdCl2 dissolution), the reaction temperature and time. Only when these conditions are strictly controlled, the obtained Pd material displays a uniformly nanoflower-like morphology, otherwise the Pd samples with nanoparticles or incomplete flowers can only be obtained. Then, the relationship between the morphology of Pd and its electrocatalytic activity was further studied. The results indicate that the Pd with perfect nanoflowers morphology possesses superior activity for formic acid electro-oxidation, while the Pd with incomplete flowers and ordinary (or irregular) particle morphology shows moderate and inferior activity. Therefore, the morphology-dependent electrocatalytic activity has been demonstrated in this work.

Graphene aerogel supported platinum nanoparticles for formic acid electro-oxidation

The performance of the direct formic acid fuel cell largely depends on the quality of the electrocatalysts used in the fuel cells. New materials are of great interest in order to improve the activity and stability of the electrocatalyst used in formic acid electro-oxidation for better direct formic acid fuel cell performance. In this study, different support materials including synthesized graphene aerogel (GA), commercial carbon black (C) or their hybrids(GA/C) were used. Platinum (Pt) nanoparticles were decorated on the defect sites of these materials by using microwave irradiation in order to improve the catalytic activity for formic acid electro-oxidation in acidic media. GA/C hybrid supports are synthesized via simple liquid mechanical mixing approach (GA/C(1)) and through hydrothermal process (GA/C(2)). Synthesized catalysts were called Pt/C, Pt/GA and Pt/GA/C(1) and Pt/GA/C(2). The as-prepared catalysts were characterized with SEM, TEM, XRD and ICP-MS. The SEM results show that GA has a 3D macroporous structure. Electrochemical measurements tests showed that either GA or GA/C material is promising support materials for Pt nanoparticles towards formic acid electro-oxidaiton. The electrochemical test results revealed that the support material affect the activity. Synthesized GA supported catalysts gave better activity than synthesized commercial carbon supported catalyst for oxidation of formic acid. Pt/GA and Pt/GA/C(2) catalysts showed higher tolerance against the poisoning effect of CO and direct pathway dominated the electro-oxidation of formic acid.

Formic acid electrooxidation activity of Pt and Pt/Au catalysts: Effects of surface physical properties and irreversible adsorption of Bi

Revealing formic acid oxidation (FAO) behaviors and designing a catalyst are very important in direct formic acid fuel cell industry. Herein, we introduced various Pt substrates of Pt nanoparticles (Pt NPs), Pt deposits on Au nanoparticles (Pt/Au NPs), Pt disk, and Pt deposits on bulk Au disks (Pt/Au disk), and the catalysts modified with Bi by irreversible adsorption. For FAO in the absence of Bi-modification, the catalytic activity increased in the order of Pt disk < Pt NP < Pt/Au disk < Pt/Au NP. On the other hand, the presence of Bi on Pt surfaces enhanced the catalytic performance in the order of Pt/Au NP < Pt/Au disk ≈ Pt NP < Pt disk. The observed activities were found to be highly correlated with a synergistic effect by Bi modification and the surface physical properties of various modified Pt substrates. The single fuel cell performances of various Bi-modified Pt NPs and Pt/Au NPs were additionally examined for real application: the performances per substrate surface area, and Pt mass of Pt/Au NPs and Bi/Pt/Au NPs were better than those of Pt NP and Bi/Pt NPs. Furthermore, the presence of Bi corresponded to single cell potentials higher than those in the absence of Bi by more than 0.1 V at 100 mA cm−2. The full understanding of the effects of surface physical properties and the irreversible adsorption of Bi further deepens the catalytic pathways of formic acid oxidation.

Synthesis, characterization, and enhanced formic acid electrooxidation activity of carbon supported MnOx promoted Pd nanoparticles

Formic acid (HCOOH) is one of the promising fuels for direct liquid fed fuel cells. However, CO poisoning is a major challenge for the development of effective catalytic system for formic acid electrooxidation (FAEO). Herein, a novel CO-resistive activated carbon supported Pd-MnOx bimetallic catalyst (Pd-MnOx/C) was presented for FAEO. Pd-MnOx/C catalyst was prepared via simple and reproducible surfactant-free deposition-reduction technique. The characterization of this novel Pd-MnOx/C catalyst was performed by inductively coupled plasma-optical emission spectroscopy (ICP-OES), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), bright field transmission electron microscopy (BFTEM), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), and scanning transmission electron microscope-energy dispersive X-ray spectroscopy (STEM-EDX). The characterization results revealed that Pd and MnOx nanoparticles (NPs) were well dispersed and separately nucleated with a mean diameter of 2.9 nm on the surface of active carbon. FAEO studies were performed on both Pd-MnOx/C and Pd/C catalysts to comprehend the effect of separately formed MnOx on the electrocatalytic activity of Pd NPs. The electrochemical measurements were carried out by using Cyclic Voltammetry (CV) and Chronoamperometry (CA), CO-Strriping Voltammetry, Lineer Sweep Voltammetry (LSV), Electrochemical impedance spectroscopy (EIS) techniques. Electrochemical results revealed that FAEO was activated by the addition of MnOx. Pd0.6-Mn0.4 exhibited the optimum catalytic activity with 1.05 A/mg Pd current density. The sum of their results clearly points that the existence of MnOx NPs enhances the electrocatalytic activity of Pd NPs by increasing their CO-resistivity and durability throughout the FAEO.

WO3/C supported Pd catalysts for formic acid electro-oxidation activity

Pd-WO3/C ternary hybrid was designed as a high-efficient catalyst towards formic acid electrooxidation. WO3/C hybrids were first prepared with two different synthesis order, and then used as the supports to synthesize two kinds of Pd-WO3/C catalysts by a quick and facile microwave-assisted ethylene glycol method. Compared with Pd/C, the catalytic performances of two Pd-WO3/C catalysts towards formic acid electrooxidation are significantly enhanced. We elected the better synthesis order and optimized the best proportion of WO3 and C in the hybrid catalyst. When the mass content of WO3 is 20% of the mass of the support, Pd nanoparticles with narrower particle size distribution are more uniformly dispersed on the surface of WO3/C support than the other counterparts, resulting in the highest performance in terms of activity and stability towards formic acid oxidation among all the samples. The reasons for the performance improvement may be: first, Pd nanoparticles in Pd-WO3/C catalysts are of small size and evenly distributed; second, there may be the catalyst-support interaction between Pd and WO3, substantially improving the catalytic capability of Pd-WO3/C catalysts; finally, the hydrogen spillover effect produced by WO3 significantly expedites the dehydrogenation of formic acid on the surface of Pd-WO3/C.

Carbon-supported Pd100-XAuX alloy nanoparticles for the electrocatalytic oxidation of formic acid: Influence of metal particles composition on activity enhancement

Two series of carbon-supported Pd100-XAuX catalysts of different Au contents have been synthesized by the “water-in-oil” microemulsion method (Triton X 114, cyclohexane) using precursor solutions of low (series L) and high concentration (series H). The metal nanoparticles are characterized by XRD, electron microscopy (SEM, HRTEM) and XPS to determine their crystal structure, particles size, composition and morphology. The electrochemical measurements provide data concerning surface properties of the PdAu particles, including surface fraction of Pd and Au and the reactivity towards hydrogen sorption/desorption processes. The metal particles of low bulk Au-content (Au/Pd <1) are of high monodispersity and of smaller size than their monometallic Pd and Au counterparts, synthesized by the same method. At higher bulk Au-content (Au/Pd >1), the particle size increases approaching almost the size of Au particles. An enrichment of Pd toward the surface of all the Pd100-XAuX particles occurs, much pronounced in the samples H series. The activity of catalysts (based on the current densities, and TOF values) in the electrooxidation of formic acid (FA) is correlated with the bulk and surface composition of the Pd100-XAuX particles. The high monodispersity of the metal particle size in the studied catalysts made it possible to observe relation between FA electrooxidation activity and surface composition of the PdAu particles. The catalytically active sites formed at the Au surface fraction ca. 0.1–0.12 (Pd 0.9–0.88) display 1.6-times higher activity (TOF) as compared to pure Pd, while higher surface Au fraction strongly reduces activity. The occurrence of electronic modification of Pd by Au in the Pd100-XAuX particles also results in a reduced hydrogen solubility, accompanied by weaker PdH bonds, which might influence the poisoning ability by CO formed through electroreduction of CO2, the product of FA oxidation.

Graphene oxide-assisted facile synthesis of platinum–tellurium nanocubes with enhanced catalytic activity for formic acid electro-oxidation

In order to obtain a loaded Pt-based catalyst with enhanced high activity and stability towards formic acid electro-oxidation (FAO), PtTe nanoparticles loaded on graphene oxide (GO) were fabricated by a facile and scalable method. XRD and HRTEM results show that the morphology of PtTe particles could be affected by the additive amount of GO and Te. It is observed that the supported PtTe particles are cubic. The XPS results show the change in the Pt electronic structure after the incorporation of Te, which impedes the chemisorption of the CO intermediate and promotes the dehydrogenation pathway of FAO. By electrochemical analysis, the performance towards FAO is greatly enhanced. The mass activity of PtTe/GO-67 is at 0.45 V (versus SCE), which is 11.5 times as high as that of Pt/C The incorporation of Te atoms and the content of GO are two major parameters for tuning the crystal structure and morphology and enhancing catalytic activity.

Enhancement of the formic acid electrooxidation activity of palladium using graphene/carbon black binary carbon supports

Combinations of graphene (Gr) and carbon black (C) were employed as binary carbon supports to fabricate Pd-based electrocatalysts via one-pot co-reduction with Pd2+. The electrocatalytic performance of the resulting Pd/Gr-C catalysts during the electrooxidation of formic acid was assessed. A Pd/Gr0.3C0.7 (Gr oxide:C = 3:7, based on the precursor mass ratio) electrocatalyst exhibited better catalytic performance than both Pd/C and Pd/Gr catalysts. The current density generated by the Pd/Gr0.3C0.7 catalyst was as high as 102.14 mA mgPd−1, a value that is approximately 3 times that obtained from the Pd/C (34.40 mA mgPd−1) and 2.6 times that of the Pd/Gr material (38.50 mA mgPd−1). The anodic peak potential of the Pd/Gr0.3C0.7 was 120 mV more negative than that of the Pd/C and 70 mV more negative than that of the Pd/Gr. Scanning electron microscopy images indicated that the spherical C particles accumulated on the wrinkled graphene surfaces to form C cluster/Gr hybrids having three-dimensional nanostructures. X-ray photoelectron spectroscopy data confirmed the interaction between the Pd metal and the binary Gr-C support. The Pd/Gr0.3C0.7 also exhibited high stability, and so is a promising candidate for the fabrication of anodes for direct formic acid fuel cells. This work demonstrates a simple and cost-effective method for improving the performance of Pd-based electrocatalysts, which should have potential industrial applications.