Formic Acid Electrooxidation Research Articles

Palladium phosphide interlayer sandwiched into Pd nanocrystals for enhanced formic acid electrooxidation reaction performance

Palladium phosphide interlayer sandwiched into Pd nanocrystals for enhanced formic acid electrooxidation reaction performance

Unraveling the Electronic and Geometric Effects in Au-Pt Bimetallic Catalysts: A Comparative Study of Electrodeposition and Sputtering Techniques for Formic Acid Oxidation

A comprehensive investigation into the relationships between the electronic structure of a surface and its catalytic properties is crucial for advancing our understanding of the fundamental mechanisms driving catalytic activity. Platinum and Pt-based systems are widely recognized for their exceptional catalytic performance numerous applications. To elucidate the correlations between electronic configuration and catalytic behavior, we performed a systematic study by depositing gold onto platinum surfaces. The model reaction selected for this investigation was the electrooxidation of formic acid, a reaction of particular relevance due to its role in low-temperature direct formic acid fuel cells (DFAFCs).The modification of Pt surfaces with Au has been reported extensively in the literature, with numerous studies demonstrating advantageous changes in catalytic properties upon the interaction of these two metals. However, despite the considerable attention this system has garnered, the precise mechanisms underlying these enhancements remain incompletely understood. Two predominant hypotheses have been proposed to explain these phenomena: (1) the geometric effect, whereby changes in surface morphology influence catalytic behavior, and (2) the electronic effect, which posits that alterations in electronic structure, particularly at the metal-metal interface, play a main role.In our work, we sought to distinguish between these two effects by preparing samples using two distinct methodologies: electrodeposition and sputtering. The electrodeposition technique, by its nature, tends to produce layers that are more likely to exhibit pseudomorphic growth, potentially leading to stronger electronic interactions between the deposited and substrate layers. In contrast, the sputtering method is expected to result in less coherent growth, with potentially weaker interactions. By comparing the catalytic activities of these differently prepared samples, we aimed to discern which effect – geometric or electronic – predominates in the enhancement of catalytic performance.Comprehensive characterization of the electronic properties of the samples was performed using X-ray Photoelectron Spectroscopy (XPS). Specifically, we focused on analyzing the binding energies of core levels, alongside a detailed investigation of the valence band spectra, paying particular attention to the density of states near the Fermi level and the shifts in the d-band center. These parameters are critical for understanding the electronic interactions at the Au-Pt interface. Additionally, the catalytic activity was studied through cyclic voltammetry (CV), where we observed synergistic effects in the oxidation of formic acid on both types of samples.Our findings contribute to the growing body of knowledge on the interplay between electronic and geometric factors.

Shift in Electrochemical Pathway Under Forced Periodic Operation of Potential Applied Due to Catalytic Resonance Effect

Sabatier's law is central to our understanding of catalysis. It states that the reactants will form reaction intermediates on the catalytic surface for a given catalytic reaction. Crucially, these intermediates must have an intermediate level of stability. If they are too stable, they will fail to decompose to form the product, and if they are too unstable, the catalyst will fail to activate the reaction1. The traditional strategy to design a catalyst for a reaction system is achieved by tuning the d-band filling of the catalyst (by making alloys, bimetallic, etc.) or by changing surface structure. Instead, this work demonstrates a constructive approach to shifting reaction pathways using the same catalyst. In the photo- and electrocatalysis, the shift in the reaction pathways (and selectivity) can also be achieved by operating the catalytic reactor using periodic modulation of one or multiple parameters around the steady state point2.This study considers the electrochemical oxidation of formic acid over a Pt catalyst. This reaction follows a triple pathway: direct, indirect, and formate3. The indirect pathway forms CO as an intermediate, which strongly interacts with the catalyst surface. To further oxidise CO, an OH species needs to be adsorbed to form CO2, which requires a potential above 0.8 V vs RHE. Therefore in a steady-state galvanostatic operation, the reaction shows self-oscillation within a specific current range3.This study uses a clean-electrolytic cell consisting of flame-annealed platinum wire as working and platinum mesh as a counter electrode with RHE as the reference electrode. The electrolytic cell is purged continuously with nitrogen, and gas is analysed using a gas analyser. The electrolyte consists of Suprapur 0.5 M H2SO4 and 0.2 M HCOOH. A sinusoidal voltage with a DC offset of 0.64 V vs RHE and amplitude of 0.26 V vs RHE was applied by varying frequency from 0 to 800 Hz. An enhancement in reaction rate by 1.94 times was observed at 800 Hz compared to steady-state operation at 0.9 V vs RHE. The I-V curve shows a qualitative enhancement towards the formate pathway compared to the indirect pathway above 600 Hz. The shift from indirect to formate pathway with a change in frequency above 600 Hz is further explained by the results from Electrochemical in situ Surface-enhanced attenuated total internal reflection infrared spectroscopy.Reference Chorkendorff, I. & Niemantsverdriet, J. W. Concepts of Modern Catalysis and Kinetics. Concepts Mod. Catal. Kinet. (2003). doi:10.1002/3527602658Ellwood, Th., Živković, L., Denissenko Petr, Abiev, R.Sh., Rebrov E.V., Menka Petkovska, Processes 2021, 9(11), 2046; /doi.org/10.3390/pr9112046Calderón-Cárdenas, A., Hartl, F. W., Gallas, J. A. C. & Varela, H. Modeling the triple-path electro-oxidation of formic acid on platinum: Cyclic voltammetry and oscillations. Catal. Today (2019). doi:10.1016/j.cattod.2019.04.054

Amphi-Funtional Mediator for Proton-Coupled Electron Transfer in Low-Voltage Electrocatalytic-Hydrogenation

Within renewable energy systems, proton exchange membrane (PEM) electrolyzer relies on multiple proton-coupled electron transfer (PCET) reaction on heterogeneous catalyst surface. In PEM electrolyzer, the catalytic process of hydrogen adsorption through Volmer reaction, involving the combination of a proton and an electron on surface, holds significance. Recent attention has been focused on optimizing the proton and an electron coupling by lowering the activation barrier and driving force of the hydrogen adsorption reaction. This focus is primarily on the cathodic part, involving hydrogen evolution reaction (HER) and organic electro-hydrogenation systems, initiating the formation of a surface-adsorbed hydrogen atom (H*) as first step. Among them, hydrogen spillover has emerged as a new method to reduce the activation barrier in HER and hydrogenation systems. This mechanism contains the diffusion of adsorbed H+ from hydrogen-rich to deficient surface. An optimal catalyst for hydrogen spillover is characterized by strong dissociation abilities and weak binding to dissociated hydrogen atoms. Palladium (Pd) exhibits commendable equilibrium of these features, suggesting the potential for performance improvement through alloying with other metals. However, hydrogen spillover is specific to the cathodic part, where the reactant is the surface-adsorbed hydrogen atom, and do not extend to the anodic part, which involves reactants unrelated to the adsorbed hydrogen atom.Generally, in the anodic part of the electrolyzer system, water-based reactants (H2O in acid/ OH- in based) or organic-based reactants (such as hydrazine, ethanol, and formic acid) are utilized. Nowadays, organic-based reactants are preferred in low-voltage electrolysis due to the sluggish kinetics of electro-decomposition in water-based reactants. Among them, formic acid emerges as a promising organic molecule for achieving high efficiency. Formic acid electrooxidation reaction (FAOR) theoretically exhibits a negative oxidation potential compared to both hydrogen oxidation reaction (HOR) and oxygen evolution reaction (OER): Eo = -0.17 VSHE for HCOOH/CO2 < +0 VSHE for H2/H+ < +1.23 VSHE for H2O/O2. Platinum (Pt)-based catalysts are utilized in FAOR. Unfortunately, since HCOOH oxidation occurs under more positive potential than H* desorption (0.05 V < E < 0.35 VRHE), the FAOR encounters a limitation of overpotential that exceeds the potential of H* desorption. In other words, acceleration of H* desorption on active site could be necessary for the anodic reaction. To facilitate the movement of H* in both anodic and cathodic reactions, it is essential to consider accelerating both H* adsorption and desorption on the active site to ensure the efficiency. Despite the emphasis on activating the target reaction by controlling PCET, there are limited studies on dual mechanisms of H* adsorption and desorption in catalytic system.Biological energy conversion involves a diverse array of ion-coupled electron transfer reaction. Many organisms in electron transport chain facilitate the movement of electrons from electron donors to acceptors through redox reactions, linking this electron transfer with H+ ions. Here, we report Amphi-functional mediator (AFM) molecules, as a hydrogen atom modulator. Through the electrodeposition method onto Pt and Pd, we facilitate distinct movements of H*, resulting in low overpotential and enhanced catalytic efficiency. Depending on the migration energy of H*, AFM can function as both an acceptor and donor of H* to Pt and Pd, respectively. In a hydrogen-producing electrolyzer employing FAOR as the anodic process (FAOR||HER), AFC reduced the cell potential by 1.15 V at 10 mA cm-2, improving the faradaic efficiency from 87% to 100%. In an electrochemical hydrogen-carrier-producing reactor to hydrogenate toluene to methylcyclohexane (MCH), AFM successfully generated MCH, which cannot be produced without AFM. (Figure 1) Figure 1

The performance of PdNi alloy catalysts supported on glassy carbon electrode toward formic acid electro-oxidation

In this research, PdNi alloy electrocatalysts with different compositions were prepared using the hydrothermal method and characterized using FE-SEM, EDX, and XRD analyses. The electro-oxidation of formic acid was investigated on the prepared samples using electrochemical techniques. It was observed that the electrocatalytic activity as well as the stability of samples were increased by increasing the Ni content. Among the studied samples, the PdNi4.09 sample exhibited superior electrocatalytic activity with a mass activity of 2982.46 mA/mgPd which was considerably higher than commercial Pd/C catalyst. Additionally, the PdNi4.09 sample was the most effective sample against CO intermediate poisoning. The role of Ni was attributed to the formation of Ni–O or Ni–OH entities near the Pd site that accelerated the oxidation of Pd–CO entities and therefore reduced the poisoning of Pd active sites for formic acid oxidation.

Tuning the Morphology of Heterostructured Palladium/Magnetite Nanoparticles for Enhanced Catalytic Electro-oxidation of Formic Acid

Tuning the Morphology of Heterostructured Palladium/Magnetite Nanoparticles for Enhanced Catalytic Electro-oxidation of Formic Acid

A hybrid FeOx/CoOx/Pt ternary nanocatalyst for augmented catalysis of formic acid electro-oxidation

Platinum-based catalysts that have long been used as the anodes for the formic acid electro-oxidation (FAO) in the direct formic acid fuel cells (DFAFCs) were susceptible to retrogradation in performance due to CO poisoning that impaired the technology transfer in industry. This work is designed to overcome this challenge by amending the Pt surface sequentially with nanosized cobalt (nano-CoOx, fibril texture of ca. 200 nm in particle size) and iron (nano-FeOx, nanorods of particle size and length of 80 and 253 nm, respectively) oxides. This enriched the Pt surface with oxygenated groups that boosted FAO and mitigated the CO poisoning. The unfilled d-orbitals of the transition metals and their tendency to vary their oxidations states presumed their participation in a faster mechanism of FAO. Engineering the Pt surface in this FeOx/CoOx/Pt hierarchy resulted in a remarkable activity toward FAO, that exceeded four times that of the Pt catalyst with up to ca. 2.5 times improvement in the catalytic tolerance against CO poisoning. This associated a ca. − 32 mV shift in the onset potential of FAO which increased to − 40 mV with a post-activation of the same catalyst at − 0.5 in 0.2 mol L–1 NaOH, displaying the catalyst's competitiveness in reducing overpotentials in DFAFCs. It also exhibited a favorable amelioration in the catalytic durability in long-termed chronoamperometric electrolysis. The electrochemical impedance spectroscopy and the CO stripping voltammetry were employed to elucidate the origin of enhancement.

PtPdAg nanotrees with low Pt content for high CO tolerance within formic acid and methanol electrooxidation

PtPdAg nanotrees with low Pt content for high CO tolerance within formic acid and methanol electrooxidation

PtPd catalysts dispersed on coal-based nitrogen-doped carbon nanotubes for formic acid electro-oxidation

PtPd catalysts dispersed on coal-based nitrogen-doped carbon nanotubes for formic acid electro-oxidation

Ultra-Large Two-Dimensional Metal Nanowire Networks by Microfluidic Laminar Flow Synthesis for Formic Acid Electrooxidation.

Despite the great research interest in two-dimensional metal nanowire networks (2D MNWNs) due to their large specific surface area and abundance of unsaturated coordination atoms, their controllable synthesis still remains a significant challenge. Herein, a microfluidics laminar flow-based approach is developed, enabling the facile preparation of large-scale 2D structures with diverse alloy compositions, such as PtBi, AuBi, PdBi, PtPdBi, and PtAuCu alloys. Remarkably, these 2D MNWNs can reach sizes up to submillimeter scale (~220 μm), which is significantly larger than the evolution from the 1D or 3D counterparts that typically measure only tens of nanometers. The PdBi 2D MNWNs affords the highest specific activity for formic acid (2669.1 mA mg-1) among current unsupported catalysts, which is 103.5 times higher than Pt-black, respectively. Furthermore, in situ Fourier transform infrared (FTIR) experiments provide comprehensive evidence that PdBi 2D MNWNs catalysts can effectively prevent CO* poisoning, resulting in exceptional activity and stability for the oxidation of formic acid.

Ultra‐Large Two‐Dimensional Metal Nanowire Networks by Microfluidic Laminar Flow Synthesis for Formic Acid Electrooxidation

AbstractDespite the great research interest in two‐dimensional metal nanowire networks (2D MNWNs) due to their large specific surface area and abundance of unsaturated coordination atoms, their controllable synthesis still remains a significant challenge. Herein, a microfluidics laminar flow‐based approach is developed, enabling the facile preparation of large‐scale 2D structures with diverse alloy compositions, such as PtBi, AuBi, PdBi, PtPdBi, and PtAuCu alloys. Remarkably, these 2D MNWNs can reach sizes up to submillimeter scale (~220 μm), which is significantly larger than the evolution from the 1D or 3D counterparts that typically measure only tens of nanometers. The PdBi 2D MNWNs affords the highest specific activity for formic acid (2669.1 mA mg−1) among current unsupported catalysts, which is 103.5 times higher than Pt‐black, respectively. Furthermore, in situ Fourier transform infrared (FTIR) experiments provide comprehensive evidence that PdBi 2D MNWNs catalysts can effectively prevent CO* poisoning, resulting in exceptional activity and stability for the oxidation of formic acid.

Ethylenediamine-mediated synthesis of Pd-based catalysts with enhanced electrocatalytic performances towards formic acid oxidation

Pd-based anode catalysts with superior activity are urgent for formic acid oxidation to further boost the direct formic acid fuel cells (DFAFCs) technologies. Herein, a strategy of ethylenediamine (EDA) modified Pd/C catalyst was developed by two main steps of EDA adsorbed on Vulcan XC-72 carbon by impregnation and Pd nanoparticles loaded on the freeze-dried C-EDA supports by liquid reduction method. The effects of sweep rates and concentrations of EDA on the formic acid electrooxidation were systematically studied. Results showed that the above parameter was optimized as the concentration of EDA of 0.1 mol L−1. Pd nanoparticles with even distribution were fabricated and particle sizes were in the range of 3.5–4.2 nm. In addition, Pd particle size became smaller with the addition of EDA, suggesting that EDA could induce the generation of smaller Pd. Electrochemical measurements demonstrated that the electrocatalytic activity of Pd/C-0.22EDA (1021 mA mg−1) with optimized modification concentration was improved as a factor of 3.82 than that of Pd/C (267 mA mg−1). An enhanced stability (about 41 times higher than Pd/C) and faster charge-transfer kinetics of formic acid electrooxidation were observed for Pd/C-0.22EDA catalyst. CV and CA measurements showed that the most active catalyst was made of the smallest (3.5 nm) Pd nanoparticles for Pd/C-0.22EDA catalyst. The better electrocatalytic performances of Pd/C-0.22EDA might be ascribed to evenly dispersed Pd with relatively smaller particle size, electron regulation between Pd and amine group as well as stable Pd structure.

Co and Ni Ratio Modulation‐Derived Electron Deficient Pd Trimetallic Catalysts for Enhanced Formic Acid Electrooxidation

AbstractPdCoNi trimetallic catalysts attracted extensive interest in direct formic acid fuel cells due to high poisoning resistance and high activity for formic acid electro‐oxidation (FAO). Herein, a series of Pd0.75CoxNiy/C alloys with a modulated ratio of Co and Ni are synthesized to investigate the effect of Co and Ni content on the electronic structure of Pd for FAO. The physical analysis demonstrated that the introduction of Co and Ni induces the lattice strain effect compared to monometallic Pd catalysts. As a consequence of fixing the total amount of Co and Ni, the strain effect is restricted, and the electronic perturbation of Pd is successfully regulated by varying the ratio of Co and Ni in Pd0.75CoxNiy/C trimetallic alloys. Pd loses more electrons, the bond strength of Pd−H is weakened, and FAO activity is enhanced first and then decreased as the Co content increases. Among the trimetallic catalysts, Pd0.75Co0.125Ni0.125/C trimetallic catalyst exhibits the highest current density of 3.253 mA cm−2 owing to the optimum electronic perturbation and Pd−H bond strength. This work provides a valuable guideline for future studies of Pd‐based trimetallic alloys.

Stabilizing Diluted Active Sites of Ultrasmall High-Entropy Intermetallics for Efficient Formic Acid Electrooxidation.

The poisoning of undesired intermediates or impurities greatly hinders the catalytic performances of noble metal-based catalysts. Herein, high-entropy intermetallics i-(PtPdIrRu)2FeCu (HEI) are constructed to inhibit the strongly adsorbed carbon monoxide intermediates (CO*) during the formic acid oxidation reaction. As probed by multiple-scaled structural characterizations, HEI nanoparticles are featured with partially negative Pt oxidation states, diluted Pt/Pd/Ir/Ru atomic sites and ultrasmall average size less than 2 nm. Benefiting from the optimized structures, HEI nanoparticles deliver more than 10 times promotion in intrinsic activity than that of pure Pt, and well-enhanced mass activity/durability than that of ternary i-Pt2FeCu intermetallics counterpart. In situ infrared spectroscopy manifests that both bridge and top CO* are favored on pure Pt but limited on HEI. Further theoretical elaboration indicates that HEI displayed a much weaker binding of CO* on Pt sites and sluggish diffusion of CO* among different sites, in contrast to pure Pt that CO* bound more strongly and was easy to diffuse on larger Pt atomic ensembles. This work verifies that HEIs are promising catalysts via integrating the merits of intermetallics and high-entropy alloys.

Palladium‐Boride Nanoflowers with Controllable Boron Content for Formic Acid Electrooxidation

AbstractThe rational design of the electronic structure and elemental compositions of anode electrocatalysts for formic acid electrooxidation reaction (FAOR) is paramount for realizing high‐performance direct formic acid fuel cells. Herein, palladium‐boride nanoflowers (Pd‐B NFs) with controllable boron content are rationally designed via a simple wet chemical reduction method, utilizing PdII‐dimethylglyoxime as precursor and NaBH4 as both reductant and boron source. The boron content of Pd‐B NFs can be regulated through manipulation of reaction time, accompanying with the crystal phase transition from face‐centered cubic to hexagonal close‐packed within the parent Pd lattice. The obtained Pd‐B NFs exhibit increased FAOR mass and specific activity with increasing boron content, showcasing remarkable inherent stability and anti‐poisoning capability compare to commercial Pd and platinum (Pt) nanocrystals. Notably, the sample reacted for 12 h reveals high FAOR specific activity (31.5 A m−2), which is approximately two times higher than the commercial Pd nanocrystals. Density functional theory calculations disclose that the d‐sp orbital hybridization between Pd and B modifies surface d‐band properties of Pd, thereby optimizing the adsorption of key intermediates and facilitating FAOR kinetics on the Pd surface. This study paves the way toward the utilization of metal boride‐based materials with simple synthesis methods for various electrocatalysis applications.

N-doped hollow carbon nanospheres embedded in N-doped graphene loaded with palladium nanoparticles as an efficient electrocatalyst for formic acid oxidation

Efficient electrocatalysts with a low cost, high activity and good durability play a crucial role in the use of direct formic acid fuel cells. Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCNs) embedded in an assembly of N-doped graphene (NG) with a three-dimensional (3D) porous structure by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Because of the unique porous configuration of interconnected layers doped with nitrogen atoms, the Pd/NHCN@NG catalyst with Pd nanoparticles has a large catalytic active surface area, superior electrocatalytic activity, a high steady-state current density, and a strong resistance to CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. When the HCN/GO mass ratio was 1:1, the Pd/NHCN@NG catalyst had an outstanding performance in the catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work indicates a way to produce superior carbon-based support materials for electrocatalysts, which will be beneficial for the development of fuel cells.

Influence of TiO2 coverage on activity and stability of Pd-TiO2/MWCNT-supported catalysts used in direct formic acid fuel cells

Pd and TiO2 supported on functionalized multiwall carbon nanotubes (f-MWCNTs) catalysts were investigated in formic acid electrooxidation reaction in direct formic acid fuel cell. TiO2 (5–60 wt.% loading) on f-MWCNTs was deposited using microwave-assisted hydrothermal method. 20 wt.% of Pd was deposited on TiO2/f-MWCNTs by reduction of palladium (II) chloride salt with sodium borohydride. Catalysts’ structure and composition were characterized by XRD, STEM, HR-TEM, TGA, XPS/XAES (Pd, Ti, O spectra features, density of valence states, Auger parameters). Average crystallite size of Pd and TiO2 from XRD (3–4 nm) agrees with those by HR-TEM (3–5 nm). Low TiO2 coverages (below 32wt.%) show smaller crystallites due to increased surface hydrophilicity, higher amount of TiO2 oxygen vacancies with attached Pd nanoparticles, increased density of valence states of strong Pd–TiO2 interface. In contrary, the higher coverages indicate lower amount of Pd–O–Ti, Ti–O–C, Pd–O–C interfaces, with electron charge transfer from TiO2 to f-MWCNTs, and to Pd. Catalysts activity (40–106 mWmgPd−1) and stability (5–240 h) are enhanced at low TiO2 coverages (4–8 wt.%) due to a strong Pd-TiO2 interface on oxygen vacancies, improved electron transport and a high active surface area. Oscillatory self-cleaning mechanism of Pd is due to oxidation by -OH groups (TiO2, f-MWCNTs), and hydrogen and CO spillover.

Stabilizing Diluted Active Sites of Ultrasmall High‐Entropy Intermetallics for Efficient Formic Acid Electrooxidation

The poisoning of undesired intermediates or impurities greatly hinders the catalytic performances of noble metal‐based catalysts. Herein, high‐entropy intermetallics i‐(PtPdIrRu)2FeCu (HEI) are constructed to inhibit the strongly adsorbed carbon monoxide intermediates (CO*) during the formic acid oxidation reaction. As probed by multiple‐scaled structural characterizations, HEI nanoparticles are featured with partially negative Pt oxidation states, diluted Pt/Pd/Ir/Ru atomic sites and ultrasmall average size less than 2 nm. Benefiting from the optimized structures, HEI nanoparticles deliver more than 10 times promotion in intrinsic activity than that of pure Pt, and well‐enhanced mass activity/durability than that of ternary i‐Pt2FeCu intermetallics counterpart. In situ infrared spectroscopy manifests that both bridge and top CO* are favored on pure Pt but limited on HEI. Further theoretical elaboration indicates that HEI displayed a much weaker binding of CO* on Pt sites and sluggish diffusion of CO* among different sites, in contrast to pure Pt that CO* bound more strongly and was easy to diffuse on larger Pt atomic ensembles. This work verifies that HEIs are promising catalysts via integrating the merits of intermetallics and high‐entropy alloys.

Enhanced formic acid electro-oxidation reaction over Ir,N-doped TiO2-supported Pt nanocatalyst

In this work, we prepared an Ir,N-doped TiO2 nanomaterial via a facile HNO3-assisted hydrothermal process that was used as an advanced support for nano-sized Pt nanoparticles (NPs) for the formic acid oxidation reaction (FAOR). The physical and electrochemical behaviours of the as-made Pt/Ir,N-doped TiO2 catalyst were systemically investigated through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopes coupled with energy dispersive X-ray analysis (FE-SEM/EDX mapping), transmission electron microscopy (TEM), linear sweep voltammetry (LSV), Tafel slope, CO-stripping, and chronoamperometric (CA) test. The Pt NPs (ca. 3 nm) were anchored on the Ir,N-doped TiO2 support, being formed by a mixture of rutile and brookite with a particle size of several ten nanometers. Due to the small size and uniform distribution of Pt NPs, the Pt/Ir,N-doped TiO2 catalyst had an electrochemical surface area of 79.88 m2 g−1, which was greater than that of the commercial Pt/C (77.63 m2 g−1). In terms of the FAOR, the Pt/Ir,N-doped TiO2 catalyst showed a negative FAOR onset potential, high current density (11.85 mA cm−2), and superior CO-tolerance compared to the commercially available catalyst. Also, the as-made catalyst possessed high electrochemical durability after 3600 s for testing. The enhanced FAOR efficiency was assigned to the formation of a dual-doping effect and strong interplay between Pt and TiO2-based support, which not only improved the electron transfer but also weakened the adsorption of carbonaceous species, thereby boosting the reaction kinetics. This study could open up a facile but effective strategy to promote particular electrochemical applications.

Kinetics of Formic Acid Electrooxidation on Anodically Modified Silver–Palladium Alloys

Kinetics of Formic Acid Electrooxidation on Anodically Modified Silver–Palladium Alloys