Activating MoS₂ for pH-Universal Hydrogen Evolution Catalysis

Abstract

MoS presents a promising catalyst for the hydrogen evolution reaction (HER) in water splitting, but its worse catalytic performance in neutral and alkaline media than in acidic environment may be problematic for practical application. This is because the other half reaction of water splitting, i.e., oxygen evolution reaction, often needs to be implemented in alkaline environment. Here we demonstrate a universal strategy that may be used to significantly improve the HER catalysis of MoS in all kinds of environments from acidic to alkaline, proton intercalation. Protons may be enabled to intercalate between monolayer MoS and underlying substrates or in the interlayer space of thicker MoS by two processes: electrochemically polarizing MoS at negative potentials (vs RHE) in acidic media or immersing MoS into certain acid solutions like TFSI. The improvement in catalytic performance is due to the activity enhancement of the active sites in MoS by the intercalated protons, which might be related with the effect of the intercalated protons on electrical conductance and the adsorption energy of hydrogen atoms. The enhancement in catalytic activity by the intercalated proton is very stable even in neutral and alkaline electrolytes.

H2‐Directing Strategy on In Situ Synthesis of Co‐MoS2 with Highly Expanded Interlayer for Elegant HER Activity and its Mechanism

“…Molybdenum sulfides (MoS 2 ), with stacked layers (S‐Mo‐S) binding together through van der Waals force, has attracted great attentions for HER reaction owing to its excellent catalytic activity, electrochemical stability and abundant elemental resources. [ 12–15 ] Despite the numerous advantages of MoS 2 , the related HER activity is limited by its semi‐conductive property and large inert basal planes with only edge‐site being active for HER. As a result, great efforts have been made to elevate related HER activity.…”

“…As a result, great efforts have been made to elevate related HER activity. [ 10,12–14,16–17 ] Recently, regulating interlayer spacing has been reported being efficient to tune the HER activity of MoS 2 . [ 18–23 ] Zhou et al [ 19 ] utilizing an oxygen incorporation approach successfully synthesized one type of MoS 2 with an enlarged interlayer spacing of 8.4 Å which could provide higher surface area and expose more active sites to enhance HER activity.…”

Atomic Arrangement in Metal‐Doped NiS2 Boosts the Hydrogen Evolution Reaction in Alkaline Media

“…Tr ansition metal sulfides (TMS) with high electrical transport and ideal atomic arrangement have been considered as promising noble-metal-free electrocatalysts for HER. [17][18][19][20][21][22] Previous studies have demonstrated excellent HER performance of several TMS,s uch as MoS 2 , [17] Ni 2 S 3 , [19] and CoS 2 . [20] However,t hese reported TMS-based catalysts are utilized only in acid media.…”

Surface Engineering of MoS2 via Laser‐Induced Exfoliation in Protic Solvents

“…It was suggested that such creation of S vacancies can facilitate the gliding of S atoms to form 1T phase MoS 2 . However, no 2H‐to‐1T phase transition was observed from MoS 2 in the presence of only protons . To verify the role of solvent and further understand the driving forces of 2H‐to‐1T phase transition and S vacancy formation, we performed the same laser‐assisted exfoliation of bulk MoS 2 in various solvents of different p K a values.…”