Dual Active Sites Engineering on Sea Urchin‐Like CoNiS Hollow Nanosphere for Stabilizing Oxygen Electrocatalysis via a Template‐Free Vulcanization Strategy

Abstract

Manipulating electronic structure and defects is crucial to achieve on‐demand functionalities of bimetallic sulfide catalysts for oxygen reduction/evolution reactions (ORR/OER). Here, via a vulcanization strategy, defects‐abundant NiCo2S4 needles obtained from sea urchin‐like NiCo2O4 are anchored on surface of hollow carbon‐sphere (NiCo2S4/HCS). NiCo2S4 nanoneedles (≈7.5 nm) are radially grown on shell of HCS with a cavity (254.5 m2 g−1), and their surface becomes rougher after vulcanization due to anion exchange reaction. As‐marked NiCo2S4/HCS‐3 exhibits better ORR activity (half‐wave potential of 0.89 V) and methanol tolerance than Pt/C (0.86 V). NiCo2S4/HCS‐3 shows a lower OER overpotential (310 mV) than RuO2 and retains 90.9% of initial activity after 9 h. Notably, zinc–air battery with NiCo2S4/HCS‐3 reveals highly‐stable charging/discharging voltages of 2.11/1.16 V with a negligible fading for 200 h. NiCo2S4 grown on outer/inner surfaces of HCS expands spatial distribution of active sites to enhance reactants‐electrode contact and charge transfer. Theoretical calculation shows that Co‐site with an electronic state near Fermi energy level is chiefly‐responsible for ORR, while Ni‐site mainly affords high OER activity. Bader charge analyses reveal that S doping increases the charge density and redox active sites in NiCo2S4. It sheds light on the understanding of electrocatalytic mechanisms on bimetallic sulfides for electronic device.

Ru–W Pair Sites Enabling the Ensemble Catalysis for Efficient Hydrogen Evolution

“…Water electrolysis powered by sustainable electricity offers a cost-effective and readily available approach for producing green DOI: 10.1002/advs.202303110 hydrogen and is considered as a key element in achieving future carbon neutrality. [1][2][3] The hydrogen evolution reaction (HER) plays a pivotal role in water electrolysis, but the use of noble-based anode catalysts and expensive proton exchange membranes in acidic electrolytes has led to a quest for efficient alkaline HER electro-catalysts. [4,5] Platinum (Pt) based materials have recently been considered as the benchmark and most capable electro-catalysts for HER, but their scarcity poses significant limitations for practical applications, [6] Ruthenium (Ru), as one of the platinum-group metals, is being recognized for its potential in developing efficient HER catalysts.…”

Co, Fe decorated N, S co-doped porous carbon enables high stability for the oxygen reduction reaction

“…A comparison of E 1/2 of FeCo-SNC and FeCo-NC indicates that the doping of S in FeCo-SNC can further promote the ORR performance, which is concordant with recent reports. 60,[66][67][68] Furthermore, FeCo-SNC shows a great limiting diffusion current ( j L = 5.95 mA cm −2 ) compared to FeCo-NC (5.28 mA cm −2 ), Co-NC (5.26 mA cm −2 ), and commercial Pt/C (5.32 mA cm −2 ). The large j L of FeCo-SNC is credited to its rough and porous structure and S doping, which facilitates the fast accessibility with O 2 at the same rotation speed.…”

Advanced design strategies for Fe-based metal–organic framework-derived electrocatalysts toward high-performance Zn–air batteries

“…Multiple active centers can induce electron rearrangement, altering the electronic environment on the metal surface, regulating internal electronic structure and microenvironment, and decreasing the reaction activation energy. [138][139][140][141] There are generally three forms of activity sources for bimetallic electrocatalysts (Fig. 8).…”