Sulfophobic and Vacancy Design Enables Self‐Cleaning Electrodes for Efficient Desulfurization and Concurrent Hydrogen Evolution with Low Energy Consumption

Abstract

Sulfide oxidation reaction (SOR) is one central step of electrochemical desulfurization and sulfur‐based batteries. However, the electrochemical performance of desulfurization and sulfur batteries has been severely hindered by sulfur passivation. Here, a discovery of sulfophobic phenomenon of electrocatalysts having weak interaction to sulfur species is reported. A self‐cleaning NiS2 electrode is developed to avoid the long‐perplexing passivation issue of solid sulfur during the SOR. Furthermore, sulfur‐vacancies are engineered into NiS2 lattice to synthesize v‐NiS2 for the hydrogen evolution reaction (HER). The resultant lattice expansion and electron redistribution can adjust the adsorbed hydrogen to reach a nearly thermos‐neutral state, enabling high catalytic activity for the HER. By coupling the HER and SOR, efficient desulfurization and simultaneous hydrogen production is demonstrated. Bifunctional NiS2 enables such a one‐stone‐kills‐two‐birds strategy to realize continuous electrochemical desulfurization with superior energy efficiency (1.05 gsulfur Wh−1). As a general design principle, sulfophobic electrocatalysts can improve the properties of lithium–sulfur batteries by minimizing the passivation of S8 during charge. In brief, interfacial interaction between electrocatalysts and sulfur species are systematically investigated and a sulfophobic strategy to significantly enhance the electrochemical performance of the SOR is offered.

P‐Doped NiTe2 with Te‐Vacancies in Lithium–Sulfur Batteries Prevents Shuttling and Promotes Polysulfide Conversion

“…From the Ni K ‐edge XANES (Figure 3f), the Ni valance state in NiTe 2 was estimated to be +2 by comparison with other references (Ni foil and NiO). [ 34 ] The significant edge shift to lower energy for NiTe 2− x verified reduced Ni with a valence state lower than +2 when compared with NiTe 2 . It more closely resembled +2 after P‐doping in P⊂NiTe 2− x .…”

“…This caused it to attract nearby atoms and trigger bonding reconstruction. [ 34 ] The higher Debye–Waller factor for NiTe 2− x relative to that for NiTe 2 indicated more structural disorder attributed to Te‐vacancies. [ 36 ]…”

“…This caused it to attract nearby atoms and trigger bonding reconstruction. [34] The higher Debye-Waller factor for NiTe 2−x relative to that for NiTe 2 indicated more structural disorder attributed to Te-vacancies. [36] The similar EXAFS oscillations extracted from the K-edge spectra for the three samples suggested similar spinel structures (Figure 3j and Figure S15, Supporting Information).…”

Energy‐Saving Hydrogen Production by Seawater Electrolysis Coupling Sulfion Degradation

“…[21][22][23][24][25] Specifically, the sulfion oxidation reaction (SOR, S 2− -2e − = S, −0.48 V vs RHE) is attractive to meet this desire due to rather low oxidation potential and rapid kinetics involving fewer electrons. [26][27][28] Compared to ClOR, the oxidation potential of SOR can be dramatically reduced by 1.3-1.4 V (Figure 1a). It provides the opportunity to fully avoid the hazardous chlorine chemistry for seawater electrolysis while cutting the energy expense greatly.…”

Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability‐Tuning Technology for Lithium‐Metal Anodes

“…As shown in Figure 6d, the resultant Li/soLM/LiF||S/Ru@rGO cell exhibits two typical voltage plateaus at 2.35 and 2.07 V, which correspond to the conversion reactions from long-chain S 8 to Li 2 S 4 and from Li 2 S 4 to Li 2 S 2 /Li 2 S, respectively. [76,77] A specific capacity of 1257.78 mAh g −1 was delivered in the first cycle, showing an initial CE of 99.1%. The reductive scan of the CV curves demonstrates two distinct peaks at 2.3 V and 2.05 V, which are in agreement with the two plateaus in the discharge curves.…”