Highly Porous Materials as Tunable Electrocatalysts for the Hydrogen and Oxygen Evolution Reaction

Abstract

wileyonlinelibrary.comContrarily, the OER (4OH − → O 2 + 4e − +2H 2 O in alkaline media) is more complicated due to the high number of steps involved. As in the HER, the best catalysts for the OER consist on less abundant and expensive materials such as RuO 2 or IrO 2 . Additionally, IrO 2 suffers from poor long term stability in alkaline solution. [ 6 ] Alternatives comprising more abundant and cheap materials as cobalt (Co), [ 7 ] nickel (Ni), [ 8,9 ] iron (Fe), [ 10 ] manganese (Mn), [ 11 ] their alloys (Ni-Co, Ni-Fe, Ni-Mo), oxides, [ 12 ] nitrides and carbides have been subject of intense research due to their promising electrocatalytic properties. For example, Ni based materials are considered to be one of the most effi cient non-noble electrocatalysts in alkaline solution. Moreover, modifications (i.e., alloying and doping) of Ni and nickel oxide based materials can result in higher activity, both for HER and OER. [ 13 ] One way to increase the catalytic behavior of these metals is by insertion of foreign dopants into materials possessing high surface areas. [ 14 ] Very recently, we showed the possibility to prepare highly porous Ni sponge materials embedded into amorphous C/N layers by means of a molten salt synthesis route. In general, the synthesis is considered relatively easy and safe, and a great variety of porous materials with respect to pore size distribution and surface area can be obtained. [ 15 ] Thereby, the salt can either act as the reaction medium (being inert to the desired reaction) or participate actively in the reaction. Careful design of the synthesis (salt melt composition, heating temperature, organic source, etc.) allows to tune the composition along with the chemical and the catalytic properties of the resulting material.Here we present a facile method to fabricate highly active manganese doped nickel-sponge materials for electrocatalytic applications (HER and OER). The effect of the manganese concentration on the chemical and the electrochemical properties is carefully studied. Moreover, we show that mild oxidation of these materials increases the surface area and alters the electrochemical activity. The composition, morphology and surface area of the resulting manganese doped nickel materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), high angle annular dark fi eld-scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-OES), thermo gravimetric Highly Porous Materials as Tunable Electrocatalysts for the Hydrogen and Oxygen Evolution ReactionMarc Ledendecker , Guylhaine Clavel , Markus Antonietti , and Menny Shalom * The facile preparation of highly porous, manganese doped, sponge-like nickel materials by salt melt synthesis embedded into nitrogen doped carbon for electrocatalytic applications is shown. The incorporation of manganese into the porous structure enhances the nickel ...

Evaluation of A-Site Ba2+-Deficient Ba1−xCo0.4Fe0.4Zr0.1Y0.1O3−δ Oxides as Electrocatalysts fo

“…Ba 0.95 CFZY shows the lowest η 10 of 360 mV in Ba 1− x CFZY, which is much lower than that of BSCF (430 mV). Although this value is larger than that of commercial Pt/C, it is comparable to many other homogenous-structured non-Pt catalysts (noble metal-free or transition-metal complex-based catalysts) for HER in alkaline medium, such as Ni [24], Co-NRCNTs [6], and Mn 1 Ni 1 [25]. Moreover, the Tafel plots depicted in Figure 5(b) were calculated to get an insight into the HER kinetic processes of the catalysts.…”

Single‐Atom to Single‐Atom Grafting of Pt1 onto FeN4 Center: Pt1@FeNC Multifunctional Electrocatalyst with Significantly Enhanced Properties

“…[39] On the other hand, the heteroatom pairs, e.g., Pt 1 O 2 Fe 1 in our catalyst, favor the cleavage of HOH bond (H 2 O ↔ H + OH − + e − ) and improve the kinetics of HER. [40] In addition, the grafting of Pt 1 O 2  would induce steric and electronic effects on Fe atoms in FeN 4 moieties that could also enhance the water dissociation. [41] To get deep insight into the enhanced HER performance of Pt 1 @FeNC, DFT calculations were performed.…”

Layered titanium diboride: towards exfoliation and electrochemical applications

“…Hydrogen evolution involves the reduction of protons, but the reaction often requires the help of an additional catalyst due to its sluggish kinetics for the adsorption of the protons onto the electrode surface followed by the desorption of molecular hydrogen. Many viable alternatives have been proposed, the more promising ones include graphene, 11,12 metal-based materials, 13,14 as well as transition metal dichalcogenides, [15][16][17] which are the centre of focus for catalyzing the HER lately. 7,8 This can be attributed to the very small free energy of the adsorption value, ΔG H , which is close to 0, implying enhanced reaction rates.…”