Amorphous nickel-cobalt complexes hybridized with 1T-phase molybdenum disulfide via hydrazine-induced phase transformation for water splitting

Abstract

Highly active and robust eletcrocatalysts based on earth-abundant elements are desirable to generate hydrogen and oxygen as fuels from water sustainably to replace noble metal materials. Here we report an approach to synthesize porous hybrid nanostructures combining amorphous nickel-cobalt complexes with 1T phase molybdenum disulfide (MoS2) via hydrazine-induced phase transformation for water splitting. The hybrid nanostructures exhibit overpotentials of 70 mV for hydrogen evolution and 235 mV for oxygen evolution at 10 mA cm−2 with long-term stability, which have superior kinetics for hydrogen- and oxygen-evolution with Tafel slope values of 38.1 and 45.7 mV dec−1. Moreover, we achieve 10 mA cm−2 at a low voltage of 1.44 V for 48 h in basic media for overall water splitting. We propose that such performance is likely due to the complete transformation of MoS2 to metallic 1T phase, high porosity and stabilization effect of nickel-cobalt complexes on 1T phase MoS2.

NiFe Alloy Nanoparticles with hcp Crystal Structure Stimulate Superior Oxygen Evolution Reaction Electrocatalytic Activity

“…Theh igh-resolution Ni2p spectrum of hcp-NiFe@NC reveals two regions for Ni2p 3/2 and Ni2p 1/2 and can be deconvoluted into six peaks in Figure 2a.The high intensity peaks at % 852.7 and % 869.9 eV can be assigned to the binding energies of metallic Ni species.T he peaks at % 855.5 and % 873.2 eV are belonged to the oxidized Ni species.And the peaks at % 861.1 and % 879.8 eV are satellite peaks. [16] Further Fe2p XPS survey in Figure 2b with broad Fe2p peaks presented two chemically distinct species including metallic Fe ( % 707.3 eV and % 719.0 eV) and the oxidation state of Fe species ( % 712.4 eV and % 724.2 eV). [17] Thee xistence of metallic Ni and Fe peaks is well consistent with XRD analysis and HRTEM and SAED results.T he oxidized species of Ni and Fe indicate the surfaces of alloy NPs were partially oxidized or interacted with adsorbed O 2 .The C1s peak can be fitted by three peaks centered at % 284.7 eV, % 285.9 eV,a nd % 288.4 eV,c orresponding to the CÀC, CÀN, and C=O bonds,r espectively ( Figure 2c).…”

Metallic Transition-Metal Dichalcogenide Nanocatalysts for Energy Conversion

“…The structural stabilization of metallic TMDCs as electrode materials during electrolysis is the basis of practical utilization. Our previous work 61 verified that amorphous Ni-Co complexes can stabilize 1T MoS 2 under external oxidation potentials; we propose that the reason for this is that the strain generated by the amorphous part makes the structure of 1T MoS 2 distorted. Notably, a singlewalled carbon nanotube is an excellent choice for hybridization with metallic TMDCs (e.g., MoS 2 62 and MoSe 2 63 ), which significantly benefits a high-efficiency electron/ ion transport pathway and structural stability.…”

Nickel Hydr(oxy)oxide Nanoparticles on Metallic MoS2 Nanosheets: A Synergistic Electrocatalyst for Hydrogen Evolution Reaction

“…The lattice spacing of the (002) plane is calculated to be 0.94 nm according to the Bragg equation, consistent with the measured interlayer distance from the TEM image (Figure S1d, Supporting Information). The enlargement of interlayer spacing of MoS 2 indirectly suggested the metallic 1T phase of the prepared MoS 2 54, 55. The Raman spectrum of the synthesized MoS 2 is also distinct from the commercial 2H‐MoS 2 , showing additional peaks at 146 cm −1 ( J 1 ), 233 cm −1 ( J 2 ), and 334 cm −1 ( J 3 ) which are attributed to the phonon modes in 1T‐MoS 2 superlattice structure (Figure S2b, Supporting Information) 47, 56.…”