A new simple preparation of platinum-nickel alloy nanoparticles and their characterization as an electrocatalyst for methanol oxidation

Pt-Ni alloy nanoparticles were produced by casting 2 or 10 mM H₂PtCl₆ solutions on a Ni column. The apparent particle size for the resultant Pt-Ni alloys increased with the concentration of the H₂PtCl₆ solution, while the content of Pt in the alloy decreased. The potential sweeps of 5 cycles in an H₂SO₄ aqueous solution for Pt-Ni (2 mM)/Ni and Pt-Ni (10 mM)/Ni electrodes led to electrochemical behavior similar to a polycrystalline Pt electrode, suggesting the formation of a few thin Pt layers on each Pt-Ni alloy surface. In electrochemical measurements, both Pt-Ni/Ni electrodes showed more negative onset potential of methanol oxidation and slower degradation of oxidation current of methanol than the polycrystalline Pt electrode. X-ray photoelectron spectroscopy of both Pt-Ni/Ni electrodes showed the shift of Pt4f peaks to a higher binding energy, suggesting that the increase in the d vacancy in the balance band 5d orbital of Pt contributed to the improved electrocatalytic activity and durability of the Pt-Ni/Ni electrodes.     

Adsorption and Decomposition of NH3 on Ni/Pt(111) and Ni/WC(001) Surfaces: A First-Principles Study

Density functional theory was used to study the NH₃ behavior on Ni monolayer covered Pt(111) and WC(001). The electronic structure of the surfaces, and the adsorption and decomposition of NH₃ were calculated and compared. Ni atoms in the monolayer behave different from that in Ni(111). More dz2 electrons of Ni in monolayer covered systems were shifted to other regions compared to Ni(111), charge density depletion on this orbital is crucial to NH₃ adsorption. NH₃ binds more stable on Ni/Pt(111) and Ni/WC(001) than on Ni(111), the energy barriers of the first N-H bond scission were evidently lower on Ni/Pt(111) and Ni/WC(001) than on Ni(111), these are significant to NH₃ decomposition. N recombination is the rate-limiting step, high reaction barrier implies that N₂ is produced only at high temperatures. Although WC has similar properties to Pt, differences of the electronic structure and catalytic activities are observed for Ni/Pt(111) and Ni/WC(001), the energy barrier for the rate-determined step increases on Ni/WC(001) instead of decreasing on Ni/Pt(111) when compared to Ni(111). To design cheaper and better catalysts, reducing the N recombination barrier by modifying Ni/WC(001) is a critical question to be solved.     

Platinum/Nickel Bicarbonate Heterostructures towards Accelerated Hydrogen Evolution under Alkaline Conditions

Heterostructured nanomaterials, generally have physicochemical properties that differ from those of the individual components, and thus have potential in a wide range of applications. New platinum (Pt)/nickel bicarbonate (Ni(HCO₃)₂) heterostructures are designed for an efficient alkaline hydrogen evolution reaction (HER). Notably, the specific and mass activity of Pt in Pt/Ni(HCO₃)₂ are substantially improved compared to the bare Pt nanoparticles (NPs). The Ni(HCO₃)₂ provides abundant water adsorption/dissociation sites and modulate the electronic structure of Pt, which determine the elementary reaction kinetics of alkaline HER. The Ni(HCO₃)₂ nanoplates offer a platform for the uniform dispersion of Pt NPs, ensuring the maximum exposure of active sites. The results demonstrate that, Ni(HCO₃)₂ is an effective catalyst promoter for alkaline HER.     

Utilization of Active Ni to Fabricate Pt–Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation

Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel–aluminum layered double hydroxide (NiAl–LDH) onto a Pt–Ni alloy surface. The incorporation of chemical etching of Pt–Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni‐rich Pt–Ni octahedra transform by interior erosion into Pt₃Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt₃Ni, the resulting Pt–Ni nanoframe/NiAl–LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural.     

Hydrogen production by aqueous phase reforming of sorbitol using bimetallic Ni–Pt catalysts: metal support interaction

Hydrogen was produced by Aqueous Phase Reforming (APR) of 10% (w/w) sorbitol using mono- and bi-metallic catalysts of Ni and Pt supported on alumina nano-fibre (Alnf), mesoporous ZrO₂ and mixed oxides of ceria–zirconia–silica (CZxS) with varying concentration of silica (where x is silica concentration). X-ray diffraction, TEM/EDS and temperature programmed reduction were also carried on these catalysts to study the surface properties. It was observed that co-impregnation of Pt and Ni in atomic ratio 1:12 increased the reducibility of Ni by forming an alloy. However, sequential impregnation of Ni followed by Pt does not form the bi-metallic particles to increase the Ni reducibility. Reduction peak of co-impregnated Ni–Pt/Alnf was found to be 270 °C lower than the sequentially impregnated Pt/Ni/Alnf. The presence of silica at high concentration in CZxS support decreased the reducibility of ceria by forming an amorphous layer on Ce_xZr_1?xO₂ crystals, which also decreased Ni reducibility. The rate of H₂ formation from aqueous phase sorbitol reforming was found to be highest for co-impregnated Ni–Pt catalysts followed by sequentially impregnated Pt/Ni and monometallic Ni catalyst. The H₂ activity decreased in the following order of the supports: Alnf > ZrO₂ > CZ3S > CZ7S.     

Pt–Ni alloy nanoparticles supported on multiwalled carbon nanotubes for methanol oxidation in alkaline media

The Pt–Ni alloy nanoparticles with different Pt/Ni atomic ratios supported on functionalized multiwalled carbon nanotubes surface were synthesized via an impregnation-reduction method. The nanocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. XRD demonstrated that Pt was alloyed with Ni. TEM showed that the Pt–Ni alloy nanoparticles were uniformly dispersed on the multiwalled carbon nanotubes (MWCNTs) surface, indicating appropriate amount of Ni in Pt–Ni alloy which facilitates the dispersion of nanoparticles on the MWCNT surface. XPS revealed that the Pt 4f peak in Pt–Ni/MWCNT (4:1) catalyst shifted to a lower binding energy compared with Pt/MWCNT catalyst, and nickel oxides/hydroxides such as NiO, Ni(OH)₂, and NiOOH were on the surface of Pt–Ni nanoparticles. Electrochemical data based on cyclic voltammetry and chronoamperometric curves indicated that Pt–Ni (4:1) alloy nanoparticles exhibited distinctly higher activity and better stability than those of Pt/MWCNTs toward methanol oxidation in alkaline media.     

Investigation of the Pt–Ni–Pb/C ternary alloy catalysts for methanol electrooxidation

This research is aimed to increase the activity of anodic catalysts and thus to lower noble metal loading in anodes for methanol electrooxidation. The Pt–Ni–Pb/C catalysts with different molar compositions were prepared. Their performance were tested by using a glassy carbon disk electrode through cyclic voltammetric curves in a solution of 0.5 mol L⁻¹ CH₃OH and 0.5 mol L⁻¹ H₂SO₄. The performances of Pt–Ni–Pb/C catalyst with optimum composition (the molar ratio of Pt/Ni/Pb is 5:4:1) and Pt/C (E-Tek) were also compared. Their particle sizes and structures were determined by means of X-ray diffraction (XRD). The XRD results show, compared with that of Pt/C, the lattice parameter of Pt–Ni–Pb (5:4:1)/C catalyst decreases, its diffraction peaks are shifted slightly to a higher 2θ values. This indicates the formation of an alloy involving the incorporation of Ni and Pb atoms into the fcc structure of Pt. The electrochemical measurement shows the activity of Pt–Ni–Pb/C catalyst with an atomic ratio of 5:4:1 for methanol electrooxidation is the best among all different compositions. The activity of Pt–Ni–Pb (5:4:1)/C catalyst is much higher than that of Pt/C (E-Tek).     

A Dewetted‐Dealloyed Nanoporous Pt Co‐Catalyst Formed on TiO2 Nanotube Arrays Leads to Strongly Enhanced Photocatalytic H2 Production

Pt nanoparticles are typically decorated as co‐catalyst on semiconductors to enhance the photocatalytic performance. Due to the low abundance and high cost of Pt, reaching a high activity with minimized co‐catalyst loadings is a key challenge in the field. We explore a dewetting‐dealloying strategy to fabricate on TiO₂ nanotubes nanoporous Pt nanoparticles, aiming at improving the co‐catalyst mass activity for H₂ generation. For this, we sputter first Pt‐Ni bi‐layers of controllable thickness (nm range) on highly ordered TiO₂ nanotube arrays, and then induce dewetting‐alloying of the Pt‐Ni bi‐layers by a suitable annealing step in a reducing atmosphere: the thermal treatment causes the Pt and Ni films to agglomerate and at the same time mix with each other, forming on the TiO₂ nanotube surface metal islands of a mixed PtNi composition. In a subsequent step we perform chemical dealloying of Ni that is selectively etched out from the bimetallic dewetted islands, leaving behind nanoporous Pt decorations. Under optimized conditions, the nanoporous Pt‐decorated TiO₂ structures show a>6 times higher photocatalytic H₂ generation activity compared to structures modified with a comparable loading of dewetted, non‐porous Pt. We ascribe this beneficial effect to the nanoporous nature of the dealloyed Pt co‐catalyst, which provides an increased surface‐to‐volume ratio and thus a more efficient electron transfer and a higher density of active sites at the co‐catalyst surface for H₂ evolution.     

Nickel foam-based composite electrodes for electrooxidation of methanol

Nickel foam and five nickel foam-based composite electrodes were prepared for being used as anode materials for the electrooxidation of methanol in KOH solution containing 0.1 and 1.0 M of methanol. The layered electrodes composed of nickel foam, platinum nanoparticles, polyaniline (PANI) and/or porous carbon (C) prepared in various assemblies. As shown by SEM analysis, depending on the preparation conditions, the electrodes of different morphologies were obtained. Using the cyclic voltammetry method, the oxidation of methanol on nickel foam electrode was observed in the potential range 0.4 V ↔ 0.7 V, where the Ni(OH)₂/NiOOH transformation occurred. The presence of Pt particles in electrode gave rise to the increase in electrocatalytic activity in this potential range. For electrodes containing dispersed platinum catalyst (Ni/Pt, Ni/PANI/Pt and Ni/C/Pt), the oxidation of methanol was noted also in the potential range −0.5 V ↔ 0.1 V. The electrocatalytic activities of the examined electrodes toward methanol oxidation at low potentials were in order Ni/Pt > Ni/C/Pt > Ni/PANI/Pt, whereas at high potentials in order Ni/PANI/Pt > Ni/Pt> Ni/C/Pt > Ni. Among the examined electrodes, the most resistant to cyclic poisoning appeared to be the Ni/C/Pt electrode. Presented at the 4Th Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005     

Enhancement of the electrochemical reduction of oxygen at platinum by nickel underpotential deposition

Polycrystalline Pt electrode was modified by underpotential deposition (upd) of nickel. The modification was performed by potential cycling in phosphate buffer pH 7. 0 containing NiSO₄, in which hydrogen and nickel upd processes were well separated. The maximum Ni upd coverage was found to be 0.3. Oxygen reduction was studied at bare and nickel upd-modified Pt. It was found that the reaction rate increased with increasing Ni upd coverage. At θ(Ni)=0.3, the current density was a factor of 2 higher compared to bare Pt (at the potential of 0.85 V). The capacitance of the electrode interface was determined in potential-relaxation experiments following interruption of the polarization current. It was found that the pseudocapacitance owing to a coverage by the adsorbed reaction intermediates was higher on the Ni-modified Pt surface than on bare Pt, which resulted in higher reaction rate. The influence of Ni adatoms on the surface coverage by the reaction intermediates was attributed to the inhibition of OH adsorption on Pt by OH ligands attached on neighboring Ni atoms.     

Rational Design of Pt−Pd−Ni Trimetallic Nanocatalysts for Room-Temperature Benzaldehyde and Styrene Hydrogenation

Nanostructures of the multimetallic catalysts offer great scope for fine tuning of heterogeneous catalysis, but clear understanding of the surface chemistry and structures is important to enhance their selectivity and efficiency. Focussing on a typical Pt−Pd−Ni trimetallic system, we comparatively examined the Ni/C, Pt/Ni/C, Pd/Ni/C and Pt−Pd/Ni/C catalysts synthesized by impregnation and galvanic replacement reaction. To clarify surface chemical/structural effect, the Pt−Pd/Ni/C catalyst was thermally treated at X=200, 400 or 600 °C in a H₂ reducing atmosphere, respectively termed as Pt−Pd/Ni/C−X. The as-prepared catalysts were characterized complementarily by XRD, XPS, TEM, HRTEM, HS-LEIS and STEM-EDS elemental mapping and line-scanning. All the catalysts were comparatively evaluated for benzaldehyde and styrene hydrogenation. It is shown that the “PtPd alloy nanoclusters on Ni nanoparticles” (PtPd/Ni) and the synergistic effect of the trimetallic Pt−Pd−Ni, lead to much improved catalytic performance, compared with the mono- or bi- metallic counterparts. However, with the increase of the treatment temperature of the Pt−Pd/Ni/C, the catalytic performance was gradually degraded, which was likely due to that the favourable nanostructure of fine “PtPd/Ni” was gradually transformed to relatively large “PtPdNi alloy on Ni” (PtPdNi/Ni) particles, thus decreasing the number of noble metal (Pt and Pd) active sites on the surface of the catalyst. The optimum trimetallic structure is thus the as synthesised Pt−Pd/Ni/C. This work provides a novel strategy for the design and development of highly efficient and low-cost multimetallic catalysts, e. g. for hydrogenation reactions.     

Exploration of electrodeposited platinum alloy catalysts for methanol electro-oxidation in 0.5 M H<Subscript>2</Subscript>SO<Subscript>4</Subscript>: Pt-Ni system

In this work, we examine the electrocatalytic activity of electrodeposited Platinum (Pt)-Nickel (Ni) alloy layers on an inert substrate electrode for methanol oxidation reaction. Analyses using energy-dispersive fluorescent X-ray analysis and powder X-ray diffractometry confirm alloying of Pt with Ni in a range of compositions. Steady-state polarisation measurements in 0.5 M methanol+0.5 M H₂SO₄ solutions clearly show that the onset of electro-oxidation shifts to less anodic potential values (approximately 160 mV), while also exhibiting current enhancements up to ~15 times the currents obtained for the pure Pt electrodeposit. A linear relationship between the cyclic voltammetric peak (oxidation) current and [MeOH] is observed at a scan rate of 50 mVs^–1, thus indicating reduced influence of adsorbed CO (CO_ads) surface poison. A critical composition, Pt (92%)/Ni (8%) [denoted Pt-Ni(3) alloy] is found to exhibit maximum electrocatalytic activity, beyond which the activity drops, whereas pure Ni does not catalyse the reaction. While the promotion of electro-oxidation is understood to be largely due to the alloy catalyst, surface redox species of Ni oxide formed during the electro-oxidation process may also contribute to the oxygenation of CO_ads, thereby enhancing the oxidation current. Plausible mechanisms of methanol oxidation on Pt/ transition metal alloy electrocatalysts are discussed in terms of electron transfer (in the alloy) and the role of Ni oxide species.     

Key Factors for Simultaneous Improvements of Performance and Durability of Core‐Shell Pt3Ni/Carbon Electrocatalysts Toward Superior Polymer Electrolyte Fuel Cell

It remains a big challenge to remarkably improve both oxygen reduction reaction (ORR) activity and long‐term durability of Pt?M bimetal electrocatalysts simultaneously in the harsh cathode environment toward widespread commercialization of polymer electrolyte fuel cells (PEFC). In this account we found double‐promotional effects of carbon micro coil (CMC) support on ORR performance and durability of octahedral Pt₃Ni nanoparticles (Oh Pt₃Ni/CMC). The Oh Pt₃Ni/CMC displayed remarkable improvements of mass activity (MA; 13.6 and 34.1 times) and surface specific activity (SA; 31.3 and 37.0 times) compared to those of benchmark Pt/C (TEC10E20E) and Pt/C (TEC10E50E‐HT), respectively. Notably, the Oh Pt₃Ni/CMC revealed a negligible MA loss after 50,000 triangular‐wave 1.0–1.5 V_RHE (startup/shutdown) load cycles, contrasted to MA losses of 40 % (TEC10E20E) and 21.5 % (TEC10E50E‐HT) by only 10,000 load cycles. It was also found that the SA increased exponentially with the decrease in the CO stripping peak potential in a series of Pt?M/carbon (M: Ni and Co), which predicts a maximum SA at the curve asymptote. Key factors for simultaneous improvements of performance and durability of core‐shell Pt₃Ni/carbon electrocatalysts toward superior PEFC is also discussed.     

Thermal decomposition of nickel(II), palladium(II), and platinum(II) complexes of <Emphasis Type="Italic">N</Emphasis>-allyl-<Emphasis Type="Italic">N</Emphasis>′-pyrimidin-2ylthiourea

Thermal decomposition of Ni(II), Pd(II), and Pt(II) complexes of N-pyrimidin-2ylthiourea (AllPmTu) have been studied by TG, DTG, and DTA and by electron impact (EI) mass spectra. The complexes have the molecular formulae as [Ni(AllPmTu)Cl₂(H₂O)], [Ni(AllPmTu)₂Cl₂(H₂O)₂], and [M(AllPmTu)Cl₂], where M = Pd^II or Pt^II, and [Pt(AllPmTu)₂]. The TG curves show that Ni(II) complexes decompose in three stages to yield NiO as a residue, while Pd(II) and Pt(II) decompose in two stages to yield MS residues. The initial mass losses correspond to elimination of allylamine for Pd(II) and Pt(II) complexes but, allyisothiocyanate for both Ni(II) complexes revealing that sulfur atom of thiourea part is involved in coordination to Pd(II) and Pt(II) but does not to Ni(II). Kinetic parameters (E ^#, n, ΔH ^#, ΔS ^#, ΔG ^#) of the decomposition stages are determined and correlated with bonding and structural properties of the complexes. The EI mass spectra of the complexes show fragments corresponding to the evolved and intermediate species.     

Impact of Group 10 Metals on the Solvent-Induced Disproportionation of o-Semiquinonato Complexes

The oxidation of [M^II(3,5-DTBCat)(DTBbpy)] (M=Ni ( [Ni] ), Pd ( [Pd] ), and Pt ( [Pt] ); 3,5-DTBCat=3,5-di-tert-butylcatecholato; DTBbpy=4,4′-di-tert-butyl-2,2′-bipyridine) afforded the dimeric {[Ni^II(3,5-DTBSQ)(DTBbpy)](PF₆)}₂ ( {[Ni](PF₆)}₂ ; 3,5-DTBSQ=3,5-di-tert-butylsemiquinonato) and monomeric semiquinonato (SQ) complexes [M^II(3,5-DTBSQ)(DTBbpy)](PF₆) (M=Pd ( [Pd](PF₆) ) and Pt ( [Pt](PF₆) )). The negative solvatochromic properties of the SQ complexes allowed us to estimate the relative order of their dipole moments: [Pd](PF₆) > [Pt](PF₆) > {[Ni](PF₆)}₂ . The complexes [Pd](PF₆) and [Pt](PF₆) adopt monomeric structures and are stable in CH₂Cl₂ and toluene, whereas they gradually disproportionate at room temperature to [M] and 3,5-di-tert-butylbenzoquinone (3,5-DTBBQ) in polar solvents such as THF, MeOH, EtOH, DMF, or DMSO. The results of spectroscopic studies suggested that the oxidized nickel complex adopts a monomeric structure ( [Ni](PF₆) ) in CH₂Cl₂, but a dimeric structure ( {[Ni](PF₆)}₂ ) in the other investigated solvents. In polar solvents, {[Ni](PF₆)}₂ may disproportionate to [Ni] and 3,5-DTBBQ at 323 K, thereby demonstrating a significant solvent- and metal-dependence in temperature. The relative activities of {[Ni](PF₆)}₂ and [M](PF₆) toward disproportionation are related to the electrochemically estimated K_dis values in CH₂Cl₂ and DMF. The present work demonstrates that solvent polarity and the dipole moments of the SQ complexes promote disproportionation, which can be controlled by a judicious choice of the metal ion, solvent, and temperature.     

Clathrate compounds of tetracyano complexes of nickel and platinum with phenol

The double cyanides of nickel and platinum form structures capable of enclosing also phenol, for example, as guest molecule. Such clathrates are Ni(NH₃)₂Pt(CN)₄ 2 C₆H₅OH and Ni(en)₂Pt(CN)₄ · 0.14 C₆H₅OH. In the case of the tetracyano complexes, different thermal stabilities of their clathrate compounds could be achieved by alteration of the constituents of the cage structure and also of the guest molecules. According to the thermal behaviour, the clathrates may be divided into two groups: those which release the guest molecules in the first step of thermal decomposition (Ni(NH₃)₂Pt(CN)₄· 2 C₆H₅OH), and those which lose the guest component only after partial destruction of the host cage (Ni(en)₂Pt(CN)₄ · 0.14 C₆H₅OH). The temperature ranges of loss of the guest component may determine the interval for their use in sorptive experiments. The temperature range for release of phenol from Ni(NH₃)₂Pt(CN)₄ · · 2 C₆H₅OH is 55–244°, and from Ni(en)₂Pt(CN)₄ · 0.14 C₆H₅OH is 139–284°. The model host molecules NiPt(CN)₄ · 6 H₂O and Ni(en)₃Pt(CN)₄ · 3 H₂O were also studied by thermal analysis.     

In Situ Construction of Pt–Ni NF@Ni-MOF-74 for Selective Hydrogenation of p-Nitrostyrene by Ammonia Borane

Pt–Ni nanoframes (Pt–Ni NFs) exhibit outstanding catalytic properties for several reactions owing to the large numbers of exposed surface active sites, but its stability and selectivity need to be improved. Herein, an in situ method for construction of a core–shell structured Pt-Ni NF@Ni-MOF-74 is reported using Pt–Ni rhombic dodecahedral as self-sacrificial template. The obtained sample exhibits not only 100 % conversion for the selective hydrogenation of p-nitrostyrene to p-aminostyrene conducted at room temperature, but also good selectivity (92 %) and high stability (no activity loss after fifteen runs) during the reaction. This is attributed to the Ni-MOF-74 shell in situ formed in the preparation process, which can stabilize the evolved Pt–Ni NF and donate electrons to the Pt metals that facilitate the preferential adsorption of electrophilic NO₂ group. This study opens up new vistas for the design of highly active, selective, and stable noble-metal-containing materials for selective hydrogenation reactions.     

Energy transfer from a platinum—nickel excited state to platinum clusters in quasi-one-dimensional Ba(Pt,Ni)(CN)4·nH2O crystals

Laser-induced luminescence in quasi-one-dimensional Ba(Pt, Ni)(CN)₄·nH₂O crystals has been measured from 5 to 300 K. A well-defined luminescence peak is observed, corresponding to an excited electronic state of platinum and nickel. Energy transfer from this Pt—Ni excited state to Pt(CN)₄^2? clusters is found to be very much dependent on the temperature.     

Reversible Electrocatalytic Activity of Carbon‐Supported PtxNi1−x in Hydrogen Reactions

Hydrogen oxidation and evolution reactions (HOR and HER) are studied on Pt_xNi_1?x/C materials synthesized by the bromide anion exchange method. Physicochemical characterization shows that this surfactant‐free method enables the preparation of well‐dispersed and effective catalysts for the processes involved in the anode of H₂/O₂ fuel cells (HOR) and the cathode of water electrolyzers (HER). The Pt‐based materials are modified with different Ni contents to decrease the amount of costly precious metal in the electrode materials. These modified Pt‐based materials are found to be electroactive for both reactions without additional overpotential. Kinetic parameters such as the Tafel slope, exchange (j₀) and kinetic current densities, and the rate‐determining steps of the reaction mechanisms are determined for each Pt–Ni catalyst and compared to those obtained at the Pt/C surface in alkaline medium. The high j₀ values that are obtained indicate a probable contribution of the surface structure of the catalysts due to their roughness and the presence of oxygenated Ni species even at low potentials.     

Enhancing the Hydrogen Evolution Reaction Activity of Platinum Electrodes in Alkaline Media Using Nickel–Iron Clusters

Herein, we demonstrate an easy way to improve the hydrogen evolution reaction (HER) activity of Pt electrodes in alkaline media by introducing Ni–Fe clusters. As a result, the overpotential needed to achieve a current density of 10 mA cm^?2 in H₂‐saturated 0.1 m KOH is reduced for the model single‐crystal electrodes down to about 70 mV. To our knowledge, these modified electrodes outperform any other reported electrocatalysts tested under similar conditions. Moreover, the influence of 1) Ni to Fe ratio, 2) cluster coverage, and 3) the nature of the alkali‐metal cations present in the electrolyte on the HER activity has been investigated. The observed catalytic performance likely originates from both the improved water dissociation at the Ni–Fe clusters and the subsequent optimal hydrogen adsorption and recombination at Pt atoms present at the Ni–Fe/Pt boundary.