Nanoscale Double‐Heterojunctional Electrocatalyst for Hydrogen Evolution

Abstract

The active sites and charge/mass transfer properties in electrocatalysts play vital roles in kinetics and thermodynamics of electrocatalysis, and impose direct impacts on electrocatalytic performance, which cannot be achieved by a simplex structure. As a prototype, the authors propose a double-heterojunctional nanostructure of NiS 2 /Ni 3 C@C containing NiS 2 /Ni 3 C and Ni 3 C/C heterojunctions as a general model to optimize the above issues and boost electrocatalytic performance. During the thermal reorganization, the in situ reaction between NiS 2 nanoparticles and carbon induces the formation of Ni 3 C between them and constructs tightly contacted two kinds of interfaces among the three components. The TEM and XPS reveal the intimately contacted three components and the as-constructed interacted dual interfaces, further confirming the formation of a porous double-heterojunctional nanostructure. Theoretical calculations uncover that the electron density redistribution occurs at Ni 3 C/C interface by spontaneous electron transfer from defected carbon to Ni 3 C and lower 𝚫G H* achieves at NiS 2 /Ni 3 C interface by the concentrated interfacial charge density, which favors the simultaneous realization of high catalytic activity and rapid charge/mass transfer. When applied for hydrogen evolution reaction (HER), the porous double-heterojunctional NiS 2 /Ni 3 C@C exhibits excellent HER activity and durability among all pH values. Profoundly, this special double-heterojunctional structure can provide a new model for high-performance electrocatalysts and beyond.

Multiple Interface Ni(PO3)2-CoP4/CoMoO4 Nanorods for Highly Efficient Hydrogen Evolution in Alkaline Water/Seawater Electrolysis

“…The results demonstrated that the highest performance was accomplished at an immersion Ni­(NO 3 ) 2 solution concentration of 0.75 mol·L –1 . The Nyquist plots of Ni­(PO 3 ) 2 -CoP 4 /CoMoO 4 /NF (∼0.42 Ω) exhibits the lowest charge-transferring resistance ( R ct ) at the overpotential of 20 mV than CoP 4 /CoMoO 4 /NF (∼1.70 Ω), Ni­(PO 3 ) 2 /NF (∼3.41 Ω), and CoMoO 4 /NF (∼4.93 Ω), respectively (Figure f), confirming high faradaic efficiency and rapid electron transfer …”

“…As shown in Figure 4b 4f), confirming high faradaic efficiency and rapid electron transfer. 60 The normalized polarization curves by ECSA of Ni(PO 3 ) 2 -CoP 4 /CoMoO 4 /NF still exhibit higher intrinsic activities than that of CoP 4 /CoMoO 4 /NF, Ni(PO 3 ) 2 /NF, and CoMoO 4 /NF, proving again that the multi-interface nanostructure has excellent catalytic activity for HER (Figure S18). Additionally, the turnover frequency value (Figure S19) of the Ni(PO 3 ) 2 -CoP 4 /CoMoO 4 /NF catalyst is 1.039 s −1 at the overpotential of 50 mV, which is greater than 0.329, 0.355, and 0.058 s −1 for CoP 4 /CoMoO 4 /NF, Ni(PO 3 ) 2 /NF, and CoMoO 4 /NF, respectively, demonstrating the elevated number of active sites and significantly promoted the HER performance.…”

MoS2/NiSe2/rGO Multiple-Interfaced Sandwich-like Nanostructures as Efficient Electrocatalysts for Overall Water Splitting

“…The results fully demonstrate that the NiSe 2 nanoparticles sandwiched between the two layered structures can effectively optimize the overpotential of MoS 2 /rGO. Furthermore, multiple interfacial nanostructures can greatly improve the contribution of a single interface to performance, and this new multi-interfacial nanostructure constructed by the three composites acting together can facilitate the OER performance [ 44 , 45 ].…”

Detecting and Quantifying Wavelength‐Dependent Electrons Transfer in Heterostructure Catalyst via In Situ Irradiation XPS

“…As expected, the Tafel slope of CS‐2 (201 mV dec −1 ) was smaller than SnO 2 (229 mV dec −1 ) and g‐C 3 N 4 (211 mV dec −1 ), revealing that the sluggish hydrogen evolution kinetics had been significantly accelerated after the heterojunction formed (Figure S14c , Supporting Information). [ 52 , 53 , 54 ] The photoelectrochemical performances of other composite samples were also compared to illustrate the effect of g‐C 3 N 4 content. The CS‐2 showed the highest current density among three composites.…”