Boron‐Induced Electronic‐Structure Reformation of CoP Nanoparticles Drives Enhanced pH‐Universal Hydrogen Evolution

et al. 2020

Chemistry A European J

Urchin‐type cobalt phosphide microparticles assembled by nanorod were encapsulated in a graphene framework membrane (CoP@GF), and used as a binder‐free electrode for alkali metal ion batteries. Electrochemical measurements indicate that this membrane exhibits enhanced reversible lithium, sodium, and potassium storage capabilities. Moreover, the energy storage properties of CoP@GF electrodes in alkali metal ion batteries display an order of Li>Na>K. DFT calculations on adsorption energy of CoP surfaces for Li, Na, and K indicated that CoP surfaces were more favorable to transfer electrons to Li atoms than Na and K, and the surface reactivity can be ordered as Li‐CoP>Na‐CoP>K‐CoP; thus, CoP@GF exhibits better storage capacity for lithium. This work provides experimental and theoretical basis for understanding the electrochemical performance of cobalt phosphide‐based membranes for alkali metal ion batteries.

Section: Resultsmentioning

confidence: 95%

Urchin‐Type Architecture Assembled by Cobalt Phosphide Nanorods Encapsulated in Graphene Framework as an Advanced Anode for Alkali Metal Ion Batteries

Wang

Zhu

et al. 2020

Chemistry A European J

“…Notably, at the heterointerface of 1T‐MoS 2 and CoS 2 , both of the MoS 2 and CoS 2 side exhibit ultrahigh HER activity with almost zero Δ G H of −0.01 and −0.009 eV, which are even much smaller than state‐of‐art Pt catalyst of −0.08 eV. [ 28 ] It suggests that the heterointerface is the active center for HER, leading to ultrafast hydrogen adsorption/desorption kinetics.…”

Section: Resultsmentioning

confidence: 99%

3D 1T‐MoS₂/CoS₂ Heterostructure via Interface Engineering for Ultrafast Hydrogen Evolution Reaction

Feng

et al. 2020

Small

132

properties as well as high activities. [4] However, its catalytic performance does not come up to expectations. In recent years, extensive efforts have been devoted to enhancing the catalytic performance, including decreasing the size, creating defects and doping heteroatoms. [5] Generally, the HER performance mainly relies on the intrinsic properties of catalysts. Therefore, regulating intrinsic electronic/ phase structure seems the effective strategy for highly activity catalyst. [6] To our knowledge, there are two different crystalline phases of MoS 2 based on the various arrangement of the sulphur atom. The common 2H phase (trigonal prismatic structure) possesses semiconductor property with a tunable bandgap between 1.3-1.9 eV, while the 1T phase (octahedral structure) is a metallic conductor with 10 7 times higher electrical conductivity than a 2H phase. [7] Therefore, 1T MoS 2 shows faster electron and charge injection/transfer, leading to superior catalytic activities. Furthermore, owing to the increased active sites on both basal surfaces and edges, 1T MoS 2 exhibits outstanding HER performance. [8] Unfortunately, IT phase cannot be explored from natural mines and it is difficult to get a high-yield production. [9] To date, several strategies have been developed to fabricate metallic-phase MoS 2 , including electron-beam irradiation, [10] chemical alkali metal intercalation, [11] plasma electron transfer, [12] flux method, [13] and phase-controlled synthesis. [14] However, the 1T phase is thermodynamically metastable and can be easily converted into stable 2H MoS 2. [15] Thus, a possible solution to fabricate stable 1T MoS 2 is urgently desired. In recent years, it has been reported that 1 T MoS 2 can be transformed from the 2H phase under the condition of light irradiation, electron beam, metal doping and heterointerface. [16] Particularly, the heterointerface-induced strategy is more desirable to achieve phase conversion owing to the moderate condition and high conversion rate. As we know, heterostructure can trigger a spontaneous electron transfer in the interface, which can tune the electro state of the two contacted components and optimize catalytic activities, leading to high catalytic performance. [17] More specifically, the catalytic activity can also be adjusted by lattice strain engineering and electron injection in the interface. [18] Therefore, heterostructure, with numerous exposed interfaces can not only modify the electro state but also increase the active sites for high-quality HER. However, there still remains a great challenge to fabricate 1T MoS 2 based Metallic phase (1T) MoS 2 has been regarded as an appealing material for hydrogen evolution reaction. In this work, a novel interface-induced strategy is reported to achieve stable and high-percentage 1T MoS 2 through highly active 1T-MoS 2 /CoS 2 hetero-nanostructure. Herein, a large number of heterointerfaces can be obtained by interlinked 1T-MoS 2 and CoS 2 nanosheets in situ grown from the molybdate cobalt oxide nanorod under moderat...

“…For Ni 3 S 4 , in light of the valence band theory, Ni‐3d orbitals overlap with 3p orbitals of ligand S atoms, resulting in (Ni–S) bonding bands and (Ni–S)* antibonding bands (Figure 1b). [ 19 ] The energy difference between (Ni–S) and (Ni–S)* is defined as charge transfer energy, which is depends on the electronegativity difference between Ni and S. [ 19b ] When heteroatoms with different atomic electronegativity are incorporated, the local electronic configuration and atomic arrangement of bonded Ni and adjacent S atoms can be reformed, [ 16,20 ] resulting in variable charge transfer energy, and consequently, the band position would shift as well.…”

Section: Adsorption Energy‐electronic Structure Relationshipmentioning

confidence: 99%

“…[ 15 ] Ren and co‐workers adopted electron‐deficient boron (B) as dopant to fine‐tuning the electron structure of CoP for balancing the rate H + reduction and removal of H 2 , and obtained B‐CoP catalyst achieves an ultralow overpotential at lager current density 100 mA cm −1 in both neutral and alkaline media. [ 16 ] Tan and co‐workers also reported that nonmetal doping can significantly boost the HER performance of Ni 3 Se 4 . [ 11b ] Thus, we rationally speculate that nonmetal doping can effectively reduce the energy barrier of the Volmer step and speed up the sluggish alkaline HER kinetics of Ni 3 S 4 .…”

Section: Introductionmentioning

confidence: 99%

Water Dissociation Kinetic‐Oriented Design of Nickel Sulfides via Tailored Dual Sites for Efficient Alkaline Hydrogen Evolution

Wang

Song

et al. 2020

Adv Funct Materials

168

The reaction kinetics of alkaline hydrogen evolution reactions (HER) is a trade‐off between adsorption and desorption for intermediate species (H2O, OH, and Hads). However, due to the complicated correlation between the intermediates adsorption energy and electronic states, targeted regulating the adsorption energy at the atomic level is not comprehensive. Herein, nonmetals (B, N, O, and F) are used to modulate the adsorption energy and electronic structure of Ni3S4, and propose that H2O and OH adsorption energy are correlate directly with d‐band center (εd) of transition metal Ni, and Hads adsorption energy has a linear dependence on p‐band center (εp) of nonmetal S. Direct experimental evidence is offered that in all nonmetals doping samples, Tafel slope and exchange current density can be improved regularly with the εd and εp, and F‐Ni3S4 shows the optimum activity with tiny overpotential 29 and 92 mV for harvesting current density 10 and 100 mA cm−2, respectively. Furthermore, the micro‐kinetics analysis and density functional theory calculations verify that F‐doping can efficiently reduce the energy barrier of the Volmer step, eventually accelerating the HER kinetics. This work provides atomic‐level insight into the structure‐properties relationship, and opens an avenue for kinetic‐oriented design of alkaline HER and beyond.