High-Density Defects Activating Fe-Doped Molybdenum Sulfide@N-Doped Carbon Heterostructures for Efficient Electrochemical Hydrogen Evolution

Abstract

Vacancy defects caused by doping are beneficial to optimizing the regional electronic structure and increasing exposed active sites, and it is vital to improve the efficiency of hydrogen evolution reaction (HER). Herein, we constructed the Fe-doped molybdenum sulfide encapsulated with N-doped carbon (FeMoSN@ NC), which with ultrathin edge-curled layer structure. Fe-doping realized with Prussian blue nanocages as the precursors, which plays a crucial role in the formation of ultrathin layer assembled microspheres. Experimental tests and theoretical calculations show that the Fe-doping can not only expand the interlayer of MoS 2 (∼11 Å) to obtain ultrathin layers but also embed into the in-plane location of MoS 2 to form high-density doping and vacancy defects. The regulation of regional active sites caused by Fe-doping can enhance the intrinsic catalytic activity of catalyst, including more active sites for HER, appropriate Gibbs free energy of hydrogen adsorption (−0.11 eV of Fe1 Mo -V Mo,S ), and low resistance for carrier transfer (9 Ω). FeMoSN@NC as the HER electrocatalyst exhibits efficient activity with a Tafel slope of 67 mV dec −1 and an overpotential of 150 mV at the current density of −100 mA mg −1 . The above insights provide new transition metal doping strategy for efficient molybdenum sulfide electrocatalysts with optimized active sites and increased electrochemical active area.

Harnessing the Defects at Hetero‐Interface of Transition Metal Compounds for Advanced Charge Storage: A Review

“…For instance, Xia et al constructed a Fe‐doped molybdenum sulfide (MoS 2 )@N‐doped carbon heterostructure (FeMoS@NC). [ 165 ] The Fe‐doping in MoS 2 can introduce high‐density vacancies, thus promoting the activity of the electrode material. To investigate the improved performance of FeMoSN@NC, the author carried out the DFT calculation to study the adsorption energy.…”

“…The elemental doping method can not only regulate the energy band and electronic structure, but also allow the formation of chemical bonds through the doped atoms at the hetero‐interfaces, promoting the charge transfer and reducing the volume expansion during the electrochemical reaction. [ 165,166 ] Ren et al synthesized a heterostructure formed by hybridized vanadium oxide (VO/V 2 O 3 ) and N‐doped carbon (NC) as an anode material for sodium‐ion batteries. [ 166 ] The authors analyzed the optimized geometry of the heterostructure and showed that the N doping can significantly increase the affinity of graphene for Na ions and VO.…”

“…Thus, the VO/V 2 O 3 heterostructure exhibited a high reversible capacity of 243 mAh g −1 after 100 cycles when applying a current density of 0.2 A g −1 . Similarly, the FeMoSN@NC heterostructure in the aforementioned work can also form the covalent bonding between Mo and N. [ 165 ] The formation of Mo–N bonds induces charge redistribution, where the relative content of Mo–N could directly affect the electrochemical reaction. In contrast, Mo–N bonds bring the D‐band of Mo closer to the electronic structure of the metal, which can improve the electrochemical activity.…”

Modulating the Electronic Structure on Cobalt Sites by Compatible Heterojunction Fabrication for Greatly Improved Overall Water/Seawater Electrolysis

“…Interface engineering as an effective method could improve the catalytic performance. ,− By optimizing the electronic structure of cobalt selenide, the design of multicomponent hybrid electrocatalysts (e.g., CoSe 2 @CoNi LDH and CoSe 2 /CoP) could accelerate the reaction rate of the Volmer step, and then, the catalytic process of cobalt selenide could be optimized. ,,− Although numerous electrocatalysts on interface engineering have been reported, there are few reports on designing an effective cobalt selenide-based electrocatalyst via compatible heterojunction fabrication. Actually, good interfacial compatibility is very important for improving the strength and density of interfacial bonding, which would significantly affect the catalytic activity and stability of electrocatalysts, but it is often neglected in the design of efficient electrocatalysts with an abundant heterointerface .…”

Interface Engineering of Hollow CoO/Co4S3@CoO/Co4S3 Heterojunction for Highly Stable and Efficient Electrocatalytic Overall Water Splitting

“…However, the precious metal catalysts are scarce and expensive. Therefore, more and more researchers have tried to develop many non-precious-metal-based electrocatalysts, including metal/alloy, , oxide, hydroxide, layered double metal, sulfide, phosphide, phosphate/borate, , boride, nitrite, , and other compounds. However, the electrochemistry capability of the majority of these catalysts is still not as good as that of precious metal.…”