The 1T phase of MoS2 has been widely reported to be highly active toward the hydrogen evolution reaction (HER), which is expected to restrict the competitive nitrogen reduction reaction (NRR). However, in this work, a prototype of active sites separation over 1T‐MoS2 is proposed by DFT calculations that the Mo‐edge and S atoms on the basal plane exhibit different catalytic NRR and HER selectivity, and a new role‐playing synergistic mechanism is also well enabled for the multistep NRR, which is further experimentally confirmed. More importantly, a self‐sacrificial strategy using g‐C3N4 as templates is proposed to synthesize 1T‐MoS2 with an ultrahigh 1T content (75.44%, named as CNMS, representing the composition elements of C, N, Mo, and S), which yields excellent NRR performances with an ammonia formation rate of 71.07 µg h–1 mg–1cat. at −0.5 V versus RHE and a Faradic efficiency of 21.01%. This work provides a promising new orientation of synchronizing the selectivity and activity for the multistep catalytic reactions.
Electrocatalytic nitrogen reduction reaction (NRR) offers an environmentally benign and sustainable alternative for NH3 synthesis. However, developing NRR electrocatalysts with both high activity and selectivity remains a significant challenge. Guided by the density functional theory (DFT) calculations and further verified by the experiment, a modulated MoS2 with well‐controlled S vacancies (MoS2‐Vs) is prepared as an excellent electrocatalyst for NRR, where both the activity and selectivity of NRR mightily rely on the S‐vacancy concentration. The optimized catalyst (MoS2‐7H) in a suitable S‐vacancy concentration (17.5%) is empowered with an excellent NRR activity (NH3 yield rate: 66.74 µg h−1 mg−1 at −0.6 V) and selectivity (Faradic efficiency (FE): 14.68% at −0.5 V). Further mechanistic study reveals that the NRR performance is powerfully concentration‐dependent since its activity is enhanced due to the S‐vacancy‐strengthened N2 adsorption and reduced reaction energy barrier. Simultaneously, its selectivity is synchronously improved by the steadily enhanced NRR activity and inversely suppressed hydrogen evolution reaction through limiting H2 desorption kinetics, which sets it markedly apart from other reported defective MoS2‐based catalysts.
Water splitting is regarded among the most prospective methods of generating green hydrogen. Switching electrolytes of water electrolysis from acidic to non-acidic ones will enable the use of noble-metal-free electrocatalysts and mitigate material corrosion, thus lowering the capital cost of water electrolyzers and improving their operational stability. However, increasing electrolyte pH will degrade the hydrogen evolution reaction (HER) activity because of the reduced concentration of H3O+ as reactants, making non-acidic HER sluggish. To accelerate HER, MoS2-based materials with the advantages of unique atomistic structure, low cost, and high abundance, have been considered prospective electrocatalysts to substitute for Pt in acid. Great efforts are being spent on extending MoS2-based materials into the catalysis of non-acidic HER, and their further development requires clarification of the existing challenges and current progress. However, it has not been systematically discussed yet for non-acidic HER on MoS2-based electrocatalysts. To mitigate the disparity, we systematically overview MoS2-based electrocatalysts for non-acidic HER, covering catalytic mechanisms, modulation strategies, materials development, current challenges, research progress, and perspectives. This review will contribute to the rational design of MoS2-based materials for high-performance HER in non-acidic conditions.
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