Enhancing the activity of oxygen-evolution and chlorine-evolution electrocatalysts by atomic layer deposition of TiO.

We report that TiO coatings formed atomic layer deposition (ALD) may tune the activity of IrO, RuO, and FTO for the oxygen-evolution and chlorine-evolution reactions (OER and CER). Electrocatalysts exposed to ~3-30 ALD cycles of TiO exhibited overpotentials at 10 mA cm of geometric current density that were several hundred millivolts lower than uncoated catalysts, with correspondingly higher specific activities. For example, the deposition of TiO onto IrO yielded a 9-fold increase in the OER-specific activity in 1.

General Strategy for the Synthesis of Transition Metal Phosphide Films for Electrocatalytic Hydrogen and Oxygen Evolution.

Transition metal phosphides recently have been identified as promising Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we present a general and scalable strategy for the synthesis of transition metal phosphide electrodes based on the reaction of commercially available metal foils (Fe, Co, Ni, Cu, and NiFe) with various organophosphine reagents. The resulting phosphide electrodes were found to exhibit excellent electrocatalytic HER and OER performance.

Low-Temperature Solution Synthesis of Few-Layer 1T '-MoTe2 Nanostructures Exhibiting Lattice Compression.

Molybdenum ditelluride, MoTe2 , is emerging as an important transition-metal dichalcogenide (TMD) material because of its favorable properties relative to other TMDs. The 1T ' polymorph of MoTe2 is particularly interesting because it is semimetallic with bands that overlap near the Fermi level, but semiconducting 2H-MoTe2 is more stable and therefore more accessible synthetically. Metastable 1T '-MoTe2 forms directly in solution at 300 °C as uniform colloidal nanostructures that consist of few-layer nanosheets, which appear to exhibit an approx.

Solution Synthesis of Thiospinel CuCo2S4 Nanoparticles.

CuCo2S4 is an important mixed-metal spinel-type sulfide that is typically synthesized using high-temperature solid-state reactions, which produce agglomerated particles with low surface areas that are not optimal for applications such as heterogeneous catalysis. Here, we show that highly crystalline and nonagglomerated colloidal CuCo2S4 nanoparticles can be synthesized in solution at 200 °C, which is significantly lower than previously reported methods. The CuCo2S4 nanoparticles were found to be highly active electrocatalysts for the oxygen evolution reaction (OER) under strongly alkaline conditions (1.

Colloidal Hybrid Nanoparticle Insertion Reaction for Transforming Heterodimers into Heterotrimers.

Three-component colloidal hybrid nanoparticles, which are central to a diverse array of applications, are typically synthesized using successive seeded growth steps, which are additive in nature and driven by surface chemistry considerations and material-specific preferences for nucleation and growth. Here, we describe a new nanoparticle insertion reaction for transforming heterodimers into heterotrimers, which is based on a supersaturation-precipitation pathway that shifts the driving force for heterotrimer formation away from surface-driven nucleation and growth. To demonstrate the concept, a Ge segment is inserted between the Au and Fe3O4 domains of Au-Fe3O4 heterodimers to form Au-Ge-Fe3O4 heterotrimers.

Comparison of the Performance of CoP-Coated and Pt-Coated Radial Junction n(+)p-Silicon Microwire-Array Photocathodes for the Sunlight-Driven Reduction of Water to H2(g).

The electrocatalytic performance for hydrogen evolution has been evaluated for radial-junction n(+)p-Si microwire (MW) arrays with Pt or cobalt phosphide, CoP, nanoparticulate catalysts in contact with 0.50 M H2SO4(aq). The CoP-coated (2.

Sequential Anion and Cation Exchange Reactions for Complete Material Transformations of Nanoparticles with Morphological Retention.

Ion exchange reactions of colloidal nanocrystals provide access to complex products that are synthetically challenging using traditional hot-injection methods. However, such reactions typically achieve only partial material transformations by employing either cation or anion exchange processes. It is now shown that anion and cation exchange reactions can be coupled together and applied sequentially in one integrated pathway that leads to complete material transformations of nanocrystal templates.

Electrocatalytic and photocatalytic hydrogen production from acidic and neutral-pH aqueous solutions using iron phosphide nanoparticles.

Nanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions.

Electrocatalytic hydrogen evolution using amorphous tungsten phosphide nanoparticles.

Amorphous tungsten phosphide (WP), which has been synthesized as colloidal nanoparticles with an average diameter of 3 nm, has been identified as a new electrocatalyst for the hydrogen-evolution reaction (HER) in acidic aqueous solutions. WP/Ti electrodes produced current densities of -10 mA cm(-2) and -20 mA cm(-2) at overpotentials of only -120 mV and -140 mV, respectively, in 0.50 M H2SO4(aq).

Highly active electrocatalysis of the hydrogen evolution reaction by cobalt phosphide nanoparticles.

Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H2SO4, pH 0.3).

Nanostructured nickel phosphide as an electrocatalyst for the hydrogen evolution reaction.

Nanoparticles of nickel phosphide (Ni2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange membrane-based electrolysis is operational. The catalytically active Ni2P nanoparticles were hollow and faceted to expose a high density of the Ni2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.