Effective Controlling of Ni₃S₂/MoS₂ Porous Hollow Spheres on Ni Foam by Non‐ionic Surfactant Micelles for Oxygen Evolution Reaction

Abstract

The hollow sphere structure has attracted various attention in the catalytic field due to its high specific surface. The good dispersion and morphology of hollow spheres are important to provide high active sites. It is a big challenge to control the morphology and distribution of the active materials during synthesis. Serious deformation and uneven distribution of the spheres were usually obtained due to inappropriate templates. A facile one-step hydrothermal method using micelles of triblock copolymer surfactant P123 was adopted to in-situ grow Ni 3 S 2 /MoS 2 porous hollow spheres on Ni foam with uniform distribution. The as-produced Ni 3 S 2 /MoS 2 porous hollow spheres have been demonstrated to have excellent oxygen evolution reaction catalytic performance as integrated electrodes. Low overpotentials of 314 mV and 337 mV have been achieved at current densities of 50 mA cm À 2 and 100 mA cm À 2 with a Tafel slope of 57 mV dec À 1 and an excellent long-term stability, which is better than other Ni-base material.

Ni3S2@MoS2@Ni3Si2 Seaweed‐like Hybrid Structures In‐situ Grown on Ni Foam as Efficient Bifunctional Electrocatalysts

“…The anodic peaks at 1.39 V from LSV curves of Ni 3 S 2 @MoS 2 @Ni 3 Si 2 in‐situ grown on Ni foam are assigned to the oxidation reaction of Ni species, leading to more efficient active sites. The low overpotentials of Ni 3 S 2 @MoS 2 @Ni 3 Si 2 structures in‐situ grown on Ni foam confirm their better OER catalytic activity than those of current reported Ni‐based electrocatalysts (Ni 3 S 2 /MoS 2 hollow spheres on Ni foam: η 50 =314 mV; [31] fluorine doped Ni 2 P: η 50 =∼410 mV; [27] Ni 3 S 2 : η 20 =∼300 mV; [14] NiS/C 3 N 4 : η 10 =∼334 mV [36] ), as shown in Table S2. The corresponding Tafel slopes of Ni 3 S 2 @MoS 2 @Ni 3 Si 2 ‐2 was calculated to be 53.7 mV dec −1 , which is lower than those of Ni 3 S 2 @MoS 2 @Ni 3 Si 2 ‐1 (72.2 mV dec −1 ), Ni 3 S 2 @MoS 2 @Ni 3 Si 2 ‐3 (78.7 mV dec −1 ), and Ni 3 S 2 @MoS 2 @Ni 3 Si 2 ‐4 (87.9 mV dec −1 ).…”

“…The anodic peaks at 1.39 V from LSV curves of Ni 3 S 2 @MoS 2 @Ni 3 Si 2 in-situ grown on Ni foam are assigned to the oxidation reaction of Ni species, leading to more efficient active sites. The low overpotentials of Ni 3 S 2 @MoS 2 @Ni 3 Si 2 structures in-situ grown on Ni foam confirm their better OER catalytic activity than those of current reported Ni-based electrocatalysts (Ni 3 S 2 /MoS 2 hollow spheres on Ni foam: η 50 = 314 mV; [31] fluorine doped Ni 2 P: η 50 = ~410 mV; [27] Ni 3 S 2 : η 20 = ~300 mV; [14] NiS/C 3 N 4 : η 10 = ~334 mV [36] ), as shown in Table S2.…”

“…Ni 3 S 2 /MoS 2 stacked particles on Ni foam have been experimentally verified to show poor electrocatalytic activity [31] . Electrochemical impedance spectroscopy (EIS) was performed for the seaweed‐like Ni 3 S 2 @MoS 2 @Ni 3 Si 2 hybrid structures in‐situ grown on Ni foam to analyze the interfaces between the electrodes and electrolytes during HER processes.…”

“…Ni 3 S 2 /MoS 2 stacked particles on Ni foam have been experimentally verified to show poor electrocatalytic activity. [31] Electrochemical impedance spectroscopy (EIS) was performed for the seaweed-like Ni 3 S 2 @MoS 2 @Ni 3 Si 2 hybrid structures in-situ grown on Ni foam to analyze the interfaces between the electrodes and electrolytes during HER processes. Much smaller R ct was obtained for Ni 3 S 2 @MoS 2 @Ni 3 Si 2 hybrid structures in-situ grown on Ni foam than those of Ni 3 Si 2 (~11.3 Ω cm À 2 ) in-situ grown on Ni foam or pure Ni foam (~19.7 Ω cm À 2 ) from the low frequency region of Nyquist plots (Figure 4a), suggesting a rapid electron transfer of the active structures to the conducting Ni foam for HER.…”