Electrocatalytic HER Research Articles

Different loading of Ni2P nanoparticles supported on Co-N-doped ordered macro-/mesoporous carbon for hydrogen evolution reaction

Herein, different loading of Ni2P nanoparticles anchored on 3D Co-N-doped ordered macro-/mesoporous carbon (Ni2P/CoN-OMMC) were synthesized. The optimized Ni2P/CoN-OMMC-40 ​wt% catalyst with 40 ​wt% Ni2P loading exhibits the best electrocatalytic HER activity under strong acidic conditions, showing an extremely low overpotential of 69 ​mV at 10 ​mA ​cm−2 and a small Tafel slope of 38 ​mV dec−1. The highly distributed active Ni2P nanoparticles and the unique macro-mesoporous CoN-OMMC support that is beneficial for promoting the active site exposure and mass/electron transport may contribute synergistically to the remarkable HER catalytic performance.

A concise discussion on MoS2basal plane activation toward the ennoblement of electrocatalytic HER output

The activation of the chemically inert basal plane of 2H-MoS2 can be achieved by inducing pores and generating vacancies by several other techniques toward enhanced electrocatalytic HER activity.

A unique two-phase heterostructure with cubic NiSe2 and orthorhombic NiSe2 for enhanced lithium ion storage and electrocatalysis.

Two-phase heterostructures have received tremendous attention in energy-related fields as high-performance electrode materials. However, heterogeneous interfaces are usually constructed by introducing foreign elements, which disturbs the investigation of the intrinsic effect of the two-phase heterostructure. Herein, unique heterostructures constructed with orthorhombic NiSe2 and cubic NiSe2 phases are developed, which are embedded in in situ formed porous carbon from metal-organic frameworks (MOFs) (O/C-NiSe2@C). Precisely-controlled selenylation of MOFs is crucial for the formation of the O/C-NiSe2 heterostructure. The heterogeneous interfaces with lattice dislocations and charge distribution are conducive to the high-speed transfer of electrons and ions during electrochemical processes, so as to improve the electrochemical reaction kinetics for lithium-ion storage and the hydrogen evolution reaction (HER). When used as the anode of lithium-ion batteries (LIBs), O/C-NiSe2@C shows a superior electrochemical performance to the counterparts with only the cubic phase (C-NiSe2@C), in view of the cycling performance (719.3 mA h g-1 at 0.1 A g-1 for 100 cycles; 456.3 mA h g-1 at 1 A g-1 for 1000 cycles) and rate capabilities (344.8 mA h g-1 at 4 A g-1). Furthermore, O/C-NiSe2@C also exhibits better HER properties than C-NiSe2@C, that is, much lower overpotentials of 154 mV and 205 mV in 0.5 M H2SO4 and 1 M KOH, respectively, at 10 mA cm-2, a smaller Tafel slope as well as stable electrocatalytic activities for 2000 cycles/10 h. Preliminary observations indicate that the unique orthorhombic/cubic two-phase heterostructure could significantly improve the electrochemical performance of NiSe2 without additional modifications such as doping, suggesting the O/C-NiSe2 heterostructure as a promising bifunctional electrode for energy conversion and storage applications.

Self-assembly patterns of non-metalloid silver thiolates: structural, HR-ESI-MS and stability studies.

Screening of AgNO3/AgStBu solutions in DMF, DMSO and NMP resulted in the isolation of three novel nanosized silver/thiolate complexes with a torus-like {Ag20(StBu)10} core. The structures of [NO3@Ag20(StBu)10(NO3)9(DMF)6] (1) and [NO3@Ag20(tBuS)10(NO3)8(NMP)8][NO3@Ag19(tBuS)10(NO3)8(NMP)6]2(NO3) (2) were studied by single crystal X-ray diffraction (SCXRD). The self-assembly process leading to 1 can be switched to a different outcome using Br-, resulting in [Br@Ag16(StBu)8(NO3)5(DMF)3](NO3)2 (3), which is the one of the few genuine host-guest complexes in the silver/thiolate systems. Solutions of the individual complexes in CH3CN were studied by HR-ESI-MS techniques, which revealed a dynamic behavior for each complex, driven by a redistribution of the {AgNO3} units. This dynamics results in the appearance of both cationic and anionic species, based on unchanged silver-thiolate cores. Daylight causes degradation of 3 with the formation of a composite material based on defective orthorhombic Ag2S with a porous morphology, as observed using the SEM technique. The electrocatalytic HER activity of such a material was studied.

Molybdenum and cobalt co-doped VC nanoparticles encapsulated in nanocarbon as efficient electrocatalysts for the hydrogen evolution reaction

Molybdenum and cobalt co-doped VC nanoparticles encapsulated in nanocarbon (Mo, Co-VC@C) are successfully synthesized via a one-pot calcination route, exhibiting excellent electrocatalytic HER performance.

Phosphorus doped two-dimensional CoFe2O4 nanobelts decorated with Ru nanoclusters and Co–Fe hydroxide as efficient electrocatalysts toward hydrogen generation

Phosphorus doped two-dimensional CoFe2O4 nanobelts decorated with Ru and CoFe hydroxide clusters on iron foam (CoFeOxHy–Ru/P–CoFe2O4/IF) are synthesized as efficient electrocatalysts for the highly electrocatalytic HER.

A doping-adsorption-pyrolysis strategy for constructing atomically dispersed cobalt sites anchored on a N-doped carbon framework as an efficient bifunctional electrocatalyst for hydrogen evolution and oxygen reduction.

Renewable energy technology development focuses on the exploration of economical and efficient non-precious metal catalysts to replace precious metal catalysts in electrocatalytic reactions including oxygen reduction (ORR) and hydrogen evolution (HER). Herein, we synthesized a cobalt single atom catalyst anchored on a N-doped carbon framework by a doping-adsorption-pyrolysis strategy. The optimized Co SAs/CN-3 catalyst showed excellent HER and ORR bifunctional electrocatalytic performance, which could be attributed to the highly dispersed Co–N4 active sites, large specific surface area and abundant pore structure. Density functional theory shows that the isolated active Co–N4 site shows low hydrogen adsorption Gibbs free energy, and promotes the adsorption of H and oxygen-containing intermediates in HER and ORR. This work not only provides a new idea for the construction of transition metal catalysts with atomic accuracy but also provides powerful guidance for the development of efficient bifunctional electrocatalysts.

Laser synthesis of amorphous CoSxnanospheres for efficient hydrogen evolution and nitrogen reduction reactions

Laser-induced amorphous CoSxnanospheres anchored on carbon fiber cloths are reported. Profiting from the amorphous nature of CoSx, the enhanced electrocatalytic HER and NRR performance with good proton activation and nitrogen adsorption abilities were obtained.

Layered 2D PtX2 (X = S, Se, Te) for the electrocatalytic HER in comparison with Mo/WX2 and Pt/C: are we missing the bigger picture?

A critical perspective that questions the use of PtX2 for the HER when we have a better performing Pt/C while analysing the potential ways in which PtX2 can actually be better than Pt/C.

Dual‐Regulation of Defect Sites and Vertical Conduction by Spiral Domain for Electrocatalytic Hydrogen Evolution

AbstractInsufficient active sites and weak vertical conduction are the intrinsic factors that restrict the electrocatalytic HER for transition‐metal dichalcogenides. As a prototype, we proposed a model of spiral MoTe2 to optimize collectively the above issues. The conductive atomic force microscopy of an individual spiral reveals that the retentive vertical conduction irrespective of layer thickness benefits from the connected screw dislocation lines between interlayers. Theoretical calculations uncover that the regions near the edge step of the spiral structures more easily form Te vacancies and have lower ΔGH* as extra active sites. A single spiral MoTe2‐based on‐chip microcell was fabricated to extract HER activity and achieved an ultrahigh current density of 3000 mA cm−2 at an overpotential of 0.4 V, which is about two orders of magnitude higher than the exfoliated counterpart. Profoundly, this unusual spiral model will initiate a new pathway for triggering other inert catalytic reactions.

A facile preparation of sulfur doped nickel–iron nanostructures with improved HER and supercapacitor performance

Since the use of diverse synthesis approaches can induce the variation in the density of active sites, which impacts electrocatalytic performance, the strategy utilized to fabricate the electrode materials for energy devices is just as important as the materials themselves. Herein, porous NiFe-oxide nanoflowers (NiFe-NFs) and macroparticles (NiFe-MPs) and corresponding S-doped NiFe-oxide nanoflowers (NiFeS-NFs) and macroparticles (NiFeS-MPs) were fabricated using facile co-precipitation and hydrothermal-sulfurization strategies, respectively. The prepared NiFe-NFs, NiFeS-NFs, NiFe-MPs, and NiFeS-MPs materials were investigated for their electrocatalytic HER in 1 M KOH electrolyte. The results indicated that NiFe-NFs displayed an overpotential of 177 mV @ 10 mA/cm2 for HER, whereas the NiFe-MPs, having similar composition, exhibited a high HER overpotential of 187 mV @ 10 mA/cm2. The enhanced HER catalytic performance of NiFe-NFs was attributed to the extensive exposure of active sites at the edges and vertices of nanocubes in the NFs-architecture. Moreover, after sulfurization, NiFeS-NFs and NiFeS-MPs demonstrated a considerable enhancement in their HER activity (54 mV and 152 mV @ 10 mA/cm2, respectively) as compared to un-sulfurized materials, which can be attributed to the enhanced conductivity of materials after S-doping, as supported by theoretical studies. Further, the capacitance experiments showed a significant increment in specific capacitances of NFs and MPs after sulfurization, from 69 to 604 F/g and from 185 to 514 F/g, respectively. This work shows that morphological and compositional changes in metal oxide-based materials may considerably enhance their catalytic activity and capacitance.

Dual‐Regulation of Defect Sites and Vertical Conduction by Spiral Domain for Electrocatalytic Hydrogen Evolution

AbstractInsufficient active sites and weak vertical conduction are the intrinsic factors that restrict the electrocatalytic HER for transition‐metal dichalcogenides. As a prototype, we proposed a model of spiral MoTe2 to optimize collectively the above issues. The conductive atomic force microscopy of an individual spiral reveals that the retentive vertical conduction irrespective of layer thickness benefits from the connected screw dislocation lines between interlayers. Theoretical calculations uncover that the regions near the edge step of the spiral structures more easily form Te vacancies and have lower ΔGH* as extra active sites. A single spiral MoTe2‐based on‐chip microcell was fabricated to extract HER activity and achieved an ultrahigh current density of 3000 mA cm−2 at an overpotential of 0.4 V, which is about two orders of magnitude higher than the exfoliated counterpart. Profoundly, this unusual spiral model will initiate a new pathway for triggering other inert catalytic reactions.

Rational construction of Ni/V-MoO2 heterostructured nanohybrids as high-performanced electrocatalysts for hydrogen evolution reaction

The development of efficient and non-precious electrocatalysts to produce hydrogen by electrolysis of water is critical to meeting the world's growing energy demand and overcoming the challenges of global warming. In this work, we have successfully synthesized a new heterostructured material in form of Ni nanoparticles modified V doped MoO2 supported by Ni foam (Ni/V-MoO2/NF) and applied it as an excellent HER electrocatalyst under alkaline conditions. The introduction of V can tune the morphology of material to be further regular, which is conducive to the exposure of active sites and mass transport. Meanwhile, the V doping and its resulting abundant oxygen vacancies can modulate the electronic structure and boost the conductivity, which benefits the improvement of electrocatalytic HER performance. Thus, compared with the non-V-doped contrast sample, the as-prepared Ni/V-MoO2/ NF has shown excellent and stable HER activity with a low overpotential of 13.1 mV at the current density of 10 mA cm−2 and Tafel slope of 34.8 mV dec−1. This work may provide positive suggestion for the design of high-performanced V-doped heterostructured electrocatalysts for various sustainable energy applications.

Cr3+ Ion‐Induced Phase Stabilization of 1T−MoSe2 with Abundant Active Sites for Efficient Hydrogen Evolution Reaction

AbstractThe electrocatalytic performance of transition metal dichalcogenides (TMDs) can be hugely impacted by their phase and electronic structure. In this regard, stabilization of the 1T (metallic) phase is a substantial challenge to attain superior electrocatalytic activity compared to its thermodynamically stable polymorph (2H phase). This report provides a simple approach to introduce the 1T phase into 2H−MoSe2 through heteroatom (Cr3+) doping using a hydrothermal method. 1T/2H−MoSe2 (x Cr) (x=1,2,3 and 5) materials have shown better electrocatalytic HER activities compared to the 2H−MoSe2, especially 2% Cr3+ doped MoSe2 (1T/2H−MoSe2 (2 Cr)) have shown the best catalytic activity. 1T/2H−MoSe2 (2 Cr) exhibits a current density of 20 mA cm−2 at an overpotential of 176 mV, low Tafel slope of 77 mV/dec, high double layer capacitance (Cdl) of 78.3 mF cm−2 and good cyclic stability. The improved electrocatalytic activity of 1T/2H−MoSe2 (2 Cr) could be attributed to the high conductance, high 1T phase content and the greater number of active sites resulting from the introduction of Cr3+ ions into MoSe2. In addition, density functional theory (DFT) studies predict that the introduction of Cr3+ ions into the MoSe2 monolayer increases the conduction electron density in the basal plane at room temperature which in turn supports the generation of additional active sites along the basal plane.

In situ growth of porous carbon with adjustable morphology on black phosphorus nanosheets for boosting electrocatalytic H2 and O2 evolution

The in situ method is proposed to improve the electrocatalytic HER and OER performances.

Construction of a self-supporting Ni2P–WO3 heterostructure for highly efficient hydrogen evolution under both caustic and acidic conditions

An amorphous Ni2P–WO3/CC based HER catalyst is constructed through a facile and scalable method. The catalyst exhibits excellent electrocatalytic HER activity and two-electrode overall water splitting performance in alkaline solutions.

Efficient homogeneous electrocatalytic hydrogen evolution using a Ni-containing polyoxometalate catalyst.

NiCl2·6H2O ([Ni(H2O)6]2Cl2) per se does not show electrocatalytic hydrogen evolution reaction activity (HER) in an acidic aqueous medium as well as in neutral water. Interestingly, when [Ni(H2O)6]2+ is present in a polyoxovanadate matrix, for example, in the compound K2[Ni(H2O)6]2[V10O28]·4H2O (1), it exhibits homogeneous electrocatalytic HER activity in an acidic aqueous solution with a turn over frequency of 2.1 s-1 and an effective low overpotential of 127 mV at pH 2.3. Compound 1 is the first nickel-containing polyoxometalate catalyst for hydrogen production via homogeneous electrocatalytic proton reduction without its decomposition under electrochemical conditions of HER.

Ru single atoms and nanoclusters on highly porous N-doped carbon as a hydrogen evolution catalyst in alkaline solutions with ultrahigh mass activity and turnover frequency

Ruthenium single atoms and ruthenium nanoclusters dispersed in hierarchically porous N-doped carbon significantly increase the Ru atom efficiency towards excellent electrocatalytic HER activity in alkaline media.

Two- and three-dimensional β,β′-N-heterocycle fused porphyrins: concise construction, singlet oxygen production and electro-catalytic hydrogen evolution reaction

A series of 2D and 3D porphyrins fused with N-heterocycles were prepared by palladium-catalyzed. Photophysical and electrochemical properties, 1O2 production and electrocatalytic HER behaviours of the representative porphyrins were investigated.

Copper bis(thiosemicarbazone) Complexes with Pendent Polyamines: Effects of Proton Relays and Charged Moieties on Electrocatalytic HER

AbstractA series of new bis(thiosemicarbazonato) Cu(II) complexes with pendent polyamines, diacetyl‐(N, ‐dimethylethylenediaminothiosemicarbazonato)‐(N’‐methyl‐3‐thio‐semicarbazonato)butane‐2,3‐diimine)‐copper(II) (Cu‐1), diacetyl‐bis(N‐dimethylethylenediamino‐3‐thiosemicarbazonato)butane‐2,3‐diimine)‐copper(II) (Cu‐3), and their cationic derivatives Cu‐2 and Cu‐4, have been synthesized and fully characterized by spectroscopic, electrochemical, and X‐ray diffraction methods. Complexes Cu‐1–Cu‐4 are analogues of Cu(ATSM), which contains a similar N2S2 donor core with terminal non‐coordinating amines. Substitution of the methyl group(s) of the terminal amines of H2ATSM with N,N‐dimethylethylenediamine followed by alkylation generates a charged quaternary amine in the ligand framework. The charged site tunes the redox potentials of the complexes with minimal changes in their physical and electronic properties. The HER activity of all four copper complexes were evaluated in acetonitrile with glacial acetic acid. All of the complexes have lower HER overpotentials than Cu(ATSM), which is attributed to charge effects. The pendent amines of Cu‐1 and Cu‐3 have the lowest HER overpotential as the pendent tertiary amine also serves as a proton relay to enhance proton rearrangement under catalytic conditions. Complex Cu‐3 showed the highest activity with a TOF of 12 × 103 s−1, an overpotential of 0.65 V, and faradaic efficiency of 100 %.