Single Semi‐Metallic Selenium Atoms on Ti₃C₂ MXene Nanosheets as Excellent Cathode for Lithium–Oxygen Batteries

Abstract

Rechargeable Li-O 2 batteries are promising due to their superior high energy density but subject to sluggish oxygen reduction/evolution kinetics. Developing highly efficient catalysts to improve catalytic activity and alleviate oxidation-reduction overpotential of Li-O 2 batteries is of great challenge and importance. Herein, a CO 2 -assisted thermal-reaction strategy is developed to fabricate isolated semi-metallic selenium single-atom-doped Ti 3 C 2 MXene catalyst (SASe-Ti 3 C 2 ) as cathodes for high-performance Li-O 2 batteries. The isolated moieties of single Se atom catalysis centers can function as active catalytic centers to drastically enhance the intrinsic LiO 2 -absorption ability and thus fundamentally modulate the formation/decomposition mechanism of lithium peroxide (Li 2 O 2 ) discharge product, thus demonstrating greatly enhanced redox kinetics and efficiently ameliorated overpotentials. Theoretical simulations reveal that the interaction between Se-involved moieties and Ti 3 C 2 substrate greatly enhances the intrinsic LiO 2 -absorption ability and fundamentally promotes the charge transfer between electrode and Li 2 O 2 product, deeply ameliorating the round-trip overpotential. The well-designed SASe-Ti 3 C 2 electrode exhibits decreased charge/discharge polarization (1.10 V vs Li/Li + ), ultrahigh discharge capacity (17 260 mAh g −1 at 100 mA g −1 ), and superior durability (170 cycles at 200 mA g −1 ) as cathode for Li-O 2 batteries. The promising results will shed light on the design of highly efficient catalysts for oxygen-involved systems of future investigation.

Modulating the Local Coordination Environment of Single‐Atom Catalysts for Enhanced Catalytic Performance in Hydrogen/Oxygen Evolution Reaction

“…[144,145] There are three known polytypes of MoS 2 , namely, 1T-, 2H-, and 3R-MoS 2 , where T, H, and R refer to tetragonal, hexagonal, and rhombohedral phases, respectively. Among these, 2H-MoS 2 is the most studied phase, due to its unique structure arrangement (central Mo atom surrounded by six sulfide ligands (S 2− )), Small 2022, 18, 2105680 [42] Copyright 2021, Wiley-VCH. b) Schematic illustration of the synthetic route of Ru SA-N-S-Ti 3 C 2 T x catalyst.…”

“…[138,139] Zhao et al adopted a CO 2 -assisted strategy to fabricate a single semi-metallic Se atom doped Ti 3 C 2 MXene catalyst (SASe-Ti 3 C 2 ). [42] The synthetic procedure is illustrated in Figure 7a. Briefly, 2D ultrathin few-layered Ti 3 C 2 Tx nanosheets were prepared via consecutive LiF/HCl etching and liquid-phase ultrasonic exfoliation treatment.…”

“…Because of this complication, the design, selection, and synthesis of solid supports have become an essential aspect of SACs development. For this purpose, high-surface-area supports like metal oxide-based materials, [21,[32][33][34][35] carbonaceous materials (i.e., activated carbon, carbon black, porous carbon, carbon nanotubes (CNT), N-doped carbon, g-C 3 N 4 , and graphene), [36][37][38][39][40][41] and 2D supports including MXenes, [42][43][44] transition metal chalcogenides, [45][46][47] layered double hydroxides (LDH), [48][49][50] and 2D metal-organic frameworks (MOFs), [51][52][53] are structurally and compositionally modified to accommodate the dispersion of high-loading single metal atoms.…”

“…Figure 7. a) Synthetic procedure of the single Se atoms on Ti 3 C 2 catalyst. Reproduced with permission [42]. Copyright 2021, Wiley-VCH.…”

Electronic “Bridge” Construction via Ag Intercalation to Diminish Catalytic Anisotropy for 2D Tin Diselenide Cathode Catalyst in Lithium–Oxygen Batteries

“…A Se surface alternative Ti 3 C 2 MXene cathode catalyst exhibited lower charge transfer and enhanced active catalytic sites. [ 13 ] V‐doped MoS 2 presented better basal plane conductivity and a higher carrier concentration. [ 14 ] Carbon nanospheres were intercalated into the layer structure to facilitate the electronic state of 2D materials.…”