Peng Liu,Jianyue Yan,Jianxin Mao,Jiawen Li,Dongxue Liang,Wenbo Song
The alkaline hydrogen evolution reaction (HER) is an extremely important reaction in energy conversion and electrolytic industries. Pristine MoS2 exhibits poor alkaline HER activity due to weak water adsorption and dissociation. Precisely manipulating active water dissociation components to form a functional interface with MoS2 would be an effective strategy. Herein, in-plane intergrowth CoS2/MoS2 ultrathin nanosheets have been achieved via a one-step pyrolytic sulfurization of a small-sized Co/Mo-MOF precursor. The in-plane intergrowth structure produced abundant interfaces and modulated the interfacial electronic structure, demonstrating an accelerated water dissociation process. Ultralow overpotentials at both onset (16 mV) and 10 mA cm−2 (75 mV) have been obtained, which surpass those of most top-rated MoS2-based materials and are even proximate to those of commercial Pt/C (0 mV at onset and 60 mV at 10 mA cm−2, respectively). Under a large current density of 400 mA cm−2, the intergrowth nanosheet exhibited long-term stability, showing potential for applications in alkaline water splitting devices.
Transition metal disulfide compounds (TMDs) catalysts exhibit excellent catalytic ability in hydrogen evolution reaction (HER), but they are susceptible to OH- poisoning under strong alkali conditions leading to active site inactivation, thus affecting their catalytic activity and stability. In this regard, we propose a catalyst “self-protection” strategy against OH - attack. Specifically, we synthesized a composite heterojunction MnMoO 4 @CoS 2 /MoS 2 on carbon cloth (CC) by a hydrothermal and calcination process. The experimental results show that MnMoO 4 undergoes reconfiguration during the HER process, and its MoO 4 2- takes the lead in dissolving in the electrolyte before being re-adsorbed on the surface of the electrocatalyst to form a protective layer, which greatly inhibits the erosion of OH - on the catalyst and effectively prevents the oxidation of the Mo 4+ and the edge S sites, which is beneficial to the long-term stability of the catalyst. The CoS 2 /MoS 2 heterojunction provides more active sites and higher conductivity to enhance its catalytic activity. The products exhibit overpotentials of only 71 and 171 mV at current densities of 10 and 100 mA cm −2 , and have long-term stability of over 100 h. In comparison, the samples after base hydrolysis treatment (deprotection) showed a significant performance decay. This study provides a novel approach for the rational design of efficient and stable TMDs catalysts.
The construction of multicomponent coupled interfaces is crucial to designing highly effective and robust bifunctional electrocatalysts for water splitting. Transition metal sulfides are widely applied as efficient catalysts, but building strong coupling interfaces to enhance electrocatalytic properties remains a tremendous challenge. Here, we reported a distinctive heterostructure electrocatalyst consisting of conductive polypyrrole (PPy)-decorated cobalt–molybdenum sulfide (CoS2/MoS2) nanosheets supported on nickel foam (CoS2/MoS2@PPy/NF) using a simple two-step hydrothermal and subsequent electrodeposition approach. Experimental results reveal that the interfacial coupling and synergistic effect between the conductive PPy and CoS2/MoS2 with tunable electronic configuration are favorable for the charge transport and the electronic structure optimization of the coupled interface, where this integrated PPy can improve the conductivity and offer a guarantee for the durability of CoS2/MoS2@PPy/NF. Density functional theory (DFT) calculations verify that electronic interaction and charge redistribution in heterogeneous CoS2/MoS2 can flexibly adjust the interfacial electronic configuration and lower the d-band center. Thanks to the advantages mentioned above, the obtained CoS2/MoS2@PPy/NF exhibits outstanding catalytic properties with the overpotentials of 46 mV for the hydrogen evolution reaction (HER) and 231 mV for the oxygen evolution reaction (OER) at 10 mA cm–2. Remarkably, assembled CoS2/MoS2@PPy/NF || CoS2/MoS2@PPy/NF only acquires 1.52 V at 10 mA cm–2 in 1.0 M KOH with a durability of 50 h. This study affords a significant reference for designing bimetallic sulfide/polymer catalysts toward high-efficiency overall water splitting.
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