Low-cost industrially available molybdenum boride and carbide as “platinum-like” catalysts for the hydrogen evolution reaction in biphasic liquid systems

Scanlon, Micheál D.; Bian, Xiaojun; Vrubel, Heron; Amstutz, Véronique; Schenk, Kurt J.; Hu, Xile; Liu, Baohong; Girault, Hubert H.

doi:10.1039/c2cp44522k

Cited by 139 publications

(156 citation statements)

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“…A burgeoning area of research is concerned with the biphasic electrocatalysis of redox reactions of interest for energy research, including the oxygen (O 2 ) reduction reaction (ORR) [9][10][11][12][13][14][15][16][17][18][19] and the hydrogen (H 2 ) evolution reaction (HER) [20][21][22][23][24][25][26][27][28], using soft interfaces functionalized with molecular species, metallic NPs or inorganic non-precious metal-based materials. The use of adsorbed solid particulate electrocatalysts at electrochemically polarisable soft interfaces has recently been reviewed by Dryfe and co-workers [29].…”

Section: Introductionmentioning

confidence: 99%

“…Whereas several reports have highlighted the catalysis of biphasic reactions by (i) facilitating the transfer of protons [12,30,31], or other ions [17], across the soft interface and (ii) the use of interfacial species, either molecular [12,32,33] or solid particulates [22,26], to coordinate reactants to enable electrocatalysis, far less common is (iii) the use of NPs as bipolar electrodes to facilitate catalysis via direct interfacial electron transfer (IET) between a lipophilic electron donor and a hydrophilic electron acceptor or vice versa [8]. Such a process is termed interfacial redox catalysis.…”

Section: Introductionmentioning

confidence: 99%

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Gold Nanofilm Redox Catalysis for Oxygen Reduction at Soft Interfaces

Smirnov

Peljo

Scanlon

et al. 2016

Electrochimica Acta

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A B S T R A C TFunctionalization of a soft or liquid-liquid interface by a one gold nanoparticle thick "nanofilm" provides a conductive pathway to facilitate interfacial electron transfer from a lipophilic electron donor to a hydrophilic electron acceptor in a process known as interfacial redox catalysis. The gold nanoparticles in the nanofilm are charged by Fermi level equilibration with the lipophilic electron donor and act as an interfacial reservoir of electrons. Additional thermodynamic driving force can be provided by electrochemically polarising the interface. Using these principles, the biphasic reduction of oxygen by a lipophilic electron donor, decamethylferrocene, dissolved in a,a,a-trifluorotoluene was catalysed at a gold nanoparticle nanofilm modified water-oil interface. A recently developed microinjection technique was utilised to modify the interface reproducibly with the mirror-like gold nanoparticle nanofilm, while the oxidised electron donor species and the reduction product, hydrogen peroxide, were detected by ion transfer voltammetry and UV/vis spectroscopy, respectively. Metallization of the soft interface allowed the biphasic oxygen reduction reaction to proceed via an alternative mechanism with enhanced kinetics and at a significantly lower overpotential in comparison to a bare soft interface. Weaker lipophilic reductants, such as ferrocene, were capable of charging the interfacial gold nanoparticle nanofilm but did not have sufficient thermodynamic driving force to significantly elicit biphasic oxygen reduction.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gold Nanofilm Redox Catalysis for Oxygen Reduction at Soft Interfaces

Smirnov

Peljo

Scanlon

et al. 2016

Electrochimica Acta

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“…[11][12][13][14] By comparison, the OER is considered the bottleneck of the overall water splitting process requiring the negotiation of multiple intermediary steps that in many cases are separated by significant energy barriers. [15][16][17] Thus, the four-electron electrooxidation of water proceeds at potentials far in excess of the thermodynamic value, necessitating an efficient electrocatalyst.…”

Section: -10mentioning

confidence: 99%

Boosting water oxidation layer-by-layer

Hidalgo-Acosta

Scanlon

Méndez

et al. 2016

Phys. Chem. Chem. Phys.

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), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO 2 /PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13).This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology.

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“…In this investigation, solid solution of Hf 0. 5 Table III) when compared to the lattice parameters of their respective stoichiometric composition. However, there are some exceptions, especially with Zrand Ta-enriched compositions.…”

Section: Resultsmentioning

confidence: 99%

“…However, several earth abundant low cost alternative materials for HER are being investigated. 3 Metal borides, such as MoB, 4,5 Co 2 B, 6 CoB, 7 and NiB 8,9 are reported as potential electrocatalysts for HER. The high catalytic activity of metal mono-borides is attributed to the electron transfer from boron to metal in the amorphous state that enriches the d-band electron density.…”

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confidence: 99%

Metal-Rich Transition Metal Diborides as Electrocatalysts for Hydrogen Evolution Reactions in a Wide Range of pH

Sitler

Raja

Charit

2016

J. Electrochem. Soc.

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Solid solutions of HfB 2 -ZrB 2 mixtures were prepared by high-energy ball milling of diboride and additive powders followed by spark plasma sintering (SPS). A mixture of stoichiometric 1:1 HfB 2 -ZrB 2 borides was the base composition to which Hf, Zr, Ta, LaB 6 or Gd 2 O 3 was added. Hf, Zr and Ta were added in order to bring the boron-to-metal ratio down to 1.86, rendering the boride as MeB 1.86 . In the case of LaB 6 and Gd 2 O 3 , 1.8 mol% was added. Electroanalytical behavior of hydrogen evolution reactions was evaluated in 1 M H 2 SO 4 and 1 M NaOH solutions. The LaB 6 additive material showed Tafel slopes of 125 and 90 mV/decade in acidic and alkaline solutions respectively. The Hf and Zr rich samples showed Tafel slopes of about 120 mV/decade in both electrolytes. The overpotentials of hydrogen evolution reactions (at 10 mA/cm 2 ) in the alkaline solution were about 100 mV lower than those in acidic solution. The metal-rich diborides and addition of LaB 6 showed better hydrogen evolution reaction (HER) activities than the base 1:1 HfB 2 -ZrB 2 stoichiometric diboride solid solution. The higher activity of metal-rich borides could be attributed to the increased electron population at the d-orbitals of the metal shown by band structure modeling calculations using the Density Functional Theory approach. The electrochemical hydrogen evolution reaction (HER) pathways on a metal surface are given by Volmer-Heyrovsky-Tafel mechanisms as follows:The Volmer reactions are considered to be the discharge or adsorption reactions, Heyrovsky reactions are the charge or desorption reactions, and Tafel's is a recombination reaction with Tafel slopes of 118, 39, 29.5 mV/decade, respectively for the Volmer, Heyrovsky and Tafel equations.2 Since HER involves successive steps of adsorption and desorption of hydrogen atoms, the electrode material should have optimal binding energy for hydrogen for enhanced electrocatalysts. Platinum groups metals have the highest catalytic properties for HER. However, several earth abundant low cost alternative materials for HER are being investigated.3 Metal borides, such as MoB, 4,5 Co 2 B, 6 CoB, 7 and NiB 8,9 are reported as potential electrocatalysts for HER. The high catalytic activity of metal mono-borides is attributed to the electron transfer from boron to metal in the amorphous state that enriches the d-band electron density. 7 The stability of the monoborides is attributed to the ability of boron to prevent the metal from oxidizing by donating electrons to stabilize the valance state and reductively remove surface oxides. 4,9 Furthermore, the lattice strains involved in the process of boron incorporation in the metal lattice is believed to lower the energy barrier for catalytic reactions. Only limited investigations have been reported on metal diborides as electrocatalysts for HER. Layered titanium diborides with and without exfoliation were investigated 10 and a significantly high overpotential of >1 V RHE was reported for a HER current density of −10 mA/cm 2 . Metal-rich borides...

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Low-cost industrially available molybdenum boride and carbide as “platinum-like” catalysts for the hydrogen evolution reaction in biphasic liquid systems

Cited by 139 publications

References 66 publications

Gold Nanofilm Redox Catalysis for Oxygen Reduction at Soft Interfaces

Gold Nanofilm Redox Catalysis for Oxygen Reduction at Soft Interfaces

Boosting water oxidation layer-by-layer

Metal-Rich Transition Metal Diborides as Electrocatalysts for Hydrogen Evolution Reactions in a Wide Range of pH

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