Lattice Strain and Composition Effects on the Methanol Oxidation Performance of Platinum-Ruthenium-Nickel Ternary Nanocatalysts.

Ternary Pt-based structures are a positive progress in addressing the disadvantages of monometallic and bimetallic Pt-based alloys for the electrochemical oxidation process of simple alcohols, which is a vital half-reaction in fuel cell technologies. We herein report a facile NaBH4-assisted ethylene glycol reduction process for fabricating a series of nanosized PtRuNi ternary alloys to explore the relationship between physicochemical properties and electrocatalytic behaviors for the acidic methanol oxidation reaction (MOR). Owing to a balance between lattice strain and synergistic effects, the Pt60Ru20Ni20/C electrocatalyst shows the highest MOR efficiency with the mass activity/specific activity of 844.48 mA mgMetal-1/1.93 mA cm-2, being a 1.94 and 2.38 times increase compared to those of the PtRu catalyst, respectively. Also, the Pt60Ru20Ni20/C catalyst possesses superior CO-tolerance and durability in strongly acidic electrolytes. This work suggests that optimizing the surface strain and electronic effects can boost the overall MOR efficiency of multicomponent Pt-based materials, which can help to further develop next-generation catalysts for energy conversion-related technologies.

Integrating Low Pt-Based Ternary NiRuPt Nanoalloy on Hybrid TiO2-Based Oxide-Carbon Composite for Enhanced Ethanol Oxidation.

Ternary NiRuPt nanoscale alloy on hybrid Ti0.9Ir0.1O2-C composite is herein reported to overcome the high cost and tenuous catalytic efficiency of anode catalysts in direct ethanol fuel cells. The small-size NiRuPt alloy is anchored on the Ti0.9Ir0.1O2-C surface via a NaBH4-ethylene glycol-assisted coreduction route. Benefiting from advantages of favorable structure and synergistic effects of compounds, the NiRuPt/Ti0.9Ir0.1O2-C catalyst exhibits high electrocatalytic performance for the ethanol electro-oxidation reaction (EOR) with mass activity of 720.75 mA mgMetal-1 and specific activity of 2.15 mA cm-2, which are 2.25- and 5-fold increases compared to those of the Pt/C (E-TEK) catalyst. The as-synthesized EOR catalyst also shows impressive anti-CO-poisoning ability and great electrocatalytic stability after 5000-cycling ADT. This work can open up an efficient strategy for designing multicomponent catalysts to reduce Pt content and enhance the catalytic performance of electrocatalysts in renewable energy-related technologies.

Mixed-oxide-containing composite-supported MoPt with ultralow Pt content for accelerating hydrogen evolution performance.

The hybridization of MoPt with ultralow Pt content (2.81 wt%) on a rutile Ti0.9Ir0.1O2-C composite (MoPt/Ti0.9Ir0.1O2-C) is fabricated by a self-growth-assisted reduction route, serving as an efficient catalyst for the hydrogen evolution reaction (HER). Due to unique structural features, the MoPt/Ti0.9Ir0.1O2-C catalyst requires an extremely low overpotential of 21.35 mV at 10 mA cm-2 and an impressive HER mass activity of 849.36 mA mgMetal-1 at 300 mV overpotential. In addition, the as-made HER electrocatalyst shows superior catalytic stability and chemical after 10 h of testing.

One-pot production of a sea urchin-like alloy electrocatalyst for the oxygen electro-reduction reaction.

Designing a cost-effective catalyst with high performance towards the oxygen electro-oxidation reaction (ORR) is of great interest for the development of green energy storage and conversion technologies. We report herein a facile self-assembly strategy in a mild reducing environment to realize an urchin-like NiPt bimetallic alloy with the domination of the (111) facets as an efficient ORR electrocatalyst. In the rotating-disk electrode test, the as-obtained NiPt nanourchins (NUCs)/C catalyst demonstrates an increase in both onset potential (0.96 VRHE) and half-wave potential (0.92 VRHE) and a direct four-electron ORR pathway with enhanced reaction kinetics. Additionally, the as-made NiPt NUCs/C electrocatalyst also shows impressive ORR catalytic stability compared to a commercial Pt NPs/C catalyst after an accelerated durability test with 15.29% degradation in mass activity, which is 3.04-times lower than 46.48% of the Pt NPs/C catalyst. The great ORR performance of the as-made catalyst is due to its unique urchin-like morphology with the dominant (111) facets and the synergistic and electronic effects of alloying Ni and Pt. This study not only provides a robust ORR electrocatalyst, but also opens a facile but effective route for fabricating 3D Pt-based binary and ternary alloy catalysts.

Wire-like Pt on mesoporous Ti0.7W0.3O2 Nanomaterial with Compelling Electro-Activity for Effective Alcohol Electro-Oxidation.

Finding out robust active and sustainable catalyst towards alcohol electro-oxidation reaction is major challenges for large-scale commercialization of direct alcohol fuel cells. Herein, a robust Pt nanowires (NWs)/Ti0.7W0.3O2 electrocatalyst, as the coherency of using non-carbon catalyst support and controlling the morphology and structure of the Pt nanocatalyst, was fabricated via an effortless chemical reduction reaction approach at room temperature without using surfactant/stabilizers or template to assemble an anodic electrocatalyst towards methanol electro-oxidation reaction (MOR) and ethanol electro-oxidation reaction (EOR). These observational results demonstrated that the Pt NWs/Ti0.7W0.3O2 electrocatalyst is an intriguing anodic electrocatalyst, which can alter the state-of-the-art Pt NPs/C catalyst. Compared with the conventional Pt NPs/C electrocatalyst, the Pt NWs/Ti0.7W0.3O2 electrocatalyst exhibited the lower onset potential (~0.1 V for MOR and ~0.2 for EOR), higher mass activity (~355.29 mA/mgPt for MOR and ~325.01 mA/mgPt for EOR) and much greater durability. The outperformance of the Pt NWs/Ti0.7W0.3O2 electrocatalyst is ascribable to the merits of the anisotropic one-dimensional Pt nanostructure and the mesoporous Ti0.7W0.3O2 support along with the synergistic effects between the Ti0.7W0.3O2 support and the Pt nanocatalyst. Furthermore, this approach may provide a promising catalytic platform for fuel cell technology and a variety of applications.

High Conductivity and Surface Area of Mesoporous Ti0.7W0.3O2 Materials as Promising Catalyst Support for Pt in Proton-Exchange Membrane Fuel Cells.

In this work, mesoporous Ti0.7W0.3O2 materials with high conductivity and surface area as promising catalyst support for Pt in Proton-Exchange Membrane Fuel Cells (PEMFCs) were synthesized via a single-step solvothermal process at low-temperature without using any surfactants or stabilizers. The characterizations of material are measured via XRD, TEM, SEM-EDS, and BET as well as electronic conductivity measurement. As a result, Ti0.7W0.3O2 formed a homogenous solid solution with mesoporous anatase-TiO2 structure and uniformly spherical nanoparticles morphology of about ~10 nm diameter, together with a high electrical conductivity of 0.022 S/cm compared to that of undoped-TiO2 (1.37×10-7 S/cm), which implied that tungsten (VI) ions was successfully doped into anatase-TiO2 lattices. The N2 adsorption/desorption isotherms indicated that Ti0.7W0.3O2 is being mesoporous structure with high surface area up to ~202 m²/g, which is nearly similar to that of the commercial Vulcan XC72 (~232 m²/g). The Pt nanoparticles was easily anchored onto Ti0.7W0.3O2 surface by the chemical reduction process using NaBH4 as a reducing agent. The spherical Pt nanoparticles of ~9 nm in diameter were deposited uniformly on the mesoporous support. These results suggested that mesoporous Ti0.7W0.3O2 materials synthesized are promising catalyst supports to replace carbon-based supports for Proton-exchange membrane fuel cells.

One-Step Hydrothermal Synthesis of a New Nanostructure Ti07Ir03O2 for Enhanced Electrical Conductivity: The Effect of pH on the Formation of Nanostructure.

Non-carbon materials are considered as the promising candidates for carbon-based catalyst support to increase the durability of proton exchange membrane fuel cells (PEMFCs). Due to the high stability and good electrical conductivity of TiO2, M-doped TiO2 (M is transition metals: Mo, Ru, V, W) is an emerging candidate for Pt nanoparticles support on the cathode side of PEMFCs. In this research, the synthesis mechanism of Ti0.7Ir0.3O2 nanostructure by the one-step hydrothermal method at low temperature was studied. We found that by only controlling the pH of the precursor solution, Ti0.7Ir0.3O2 can be synthesized with different morphology and phase selection without any formation of mixed oxides. In particular, Ti0.7Ir0.3O2 nanostructure synthesized at pH = 0 exhibited concomitant anatase, brookite, and rutile phases. The spherical particles of diameter 20-40 nm, cubic particles of 30-50 nm in side-length and rod-like particles with 70 nm in length and 20 nm in diameter represented the anatase, brookite, and rutile phases respectively. At a pH value of 1 or 2, the majority of spherical nanoparticles were homogeneous at 15-20 nm in diameter. It was observed that the electronic conductivity of novel Ti0.7Ir0.3O2 nanostructure was significantly higher than that of the undoped TiO2. Thus the promising properties of this new nanostructure open a new path to the much-needed fuel cell applications.

Advanced Ti0.7W0.3O2 Nanoparticles Prepared via Solvothermal Process Using Titanium Tetrachloride and Tungsten Hexachloride as Precursors.

The degradation of Pt-based catalysts is considered as the main barrier to the commercialization of fuel cells. M-doped TiO2 (M is a transition metal) has been investigated to improve the stability of electrocatalysts. Recently, W-doped TiO2 materials have been found as a good catalyst support for the photocatalyst applications but their application in Proton-exchange membrane fuel cell application has rarely been reported. In addition, the agglomeration of nanoparticles, which are synthesized from the organic precursor, has been reported. Here, we report Ti0.7W0.3O2 nanoparticles prepared via a one-step solvothermal method with inorganic precursors without using surfactants or stabilizers for restricting nanoparticle agglomeration. The properties of the material were measured by XRD, TEM, BET, and electronic conductivity. The mean particle size of ∼5 nm, the high specific surface area of 126.471 m2/g and a moderate electronic conductivity of 0.014 S/cm were obtained for the sample prepared at 220 °C for 4 h. It was observed that using inorganic precursors to prevent particle agglomeration is more advantageous compared to organic precursors as mentioned in previous reports.