Metal Single‐Site Molecular Complex–MXene Heteroelectrocatalysts Interspersed Graphene Nanonetwork for Efficient Dual‐Task of Water Splitting and Metal–Air Batteries

Abstract

Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (FeMC)‐carbide MXene (Mo2TiC2Tx) uniformly embedded in a 3D graphene‐based hierarchical network (GrH) is rationally designed. The coexistence of FeMC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the FeMC–MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al–air batteries derived from FeMC–MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm−2, respectively. Impressively, the liquid‐state Zn–air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm−2 and 1.86 V at 0.4 A cm−2 in 30 wt.% KOH at 80 °C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.

Deep Electronic State Regulation through Unidirectional Cascade Electron Transfer Induced by Dual Junction Boosting Electrocatalysis Performance

“…We can observe the characteristic diffraction peaks of FePc, L-Ti 3 C 2 -R, and g-C 3 N 4 in the X-ray diffraction (XRD) pattern of FePc/L-R/CN (Figure S6, Supporting Information), confirming the formation of ternary heterostructures. [29] The similar FT-IR spectra of FePc/L-R/CN and g-C 3 N 4 indicated that the integration of FePc and L-Ti 3 C 2 -R shows negligible effect in structure for the internal g-C 3 N 4 and the uniform dispersion of FePc/L-R on g-C 3 N 4 nanosheets consistent with the XRD analysis (Figure S7, Supporting Information). [30] Compared with FePc/L-OH, FePc/L-OH/CN shows a typical IV-type isothermal curve with a significant hysteresis return line and an increased number of mesopores (Figure S8, Supporting Information), which provided a larger specific surface area and higher porosity to promote electrolyte transport.…”

Allying interfacial engineering of 2D carbon nanosheet‐, graphene‐, and graphdiyne‐based heterostructured electrocatalysts toward hydrogen evolution and overall water splitting

“…We believe such a finding will inspire more innovative structural designs with unprecedented combinations of components in the future. 178 Aside from the pristine graphene substrate without doping or defect engineering in the heterostructures, many researchers have also extended their interests in heteroatom-doped graphene, including the commonly applied 2D graphene doped with N, 179-181 S, 182 P, 183,184 and B, 185 as well as defect-rich graphene, 186 to construct the electrocatalysts. The heteroatom dopants and defects in graphene plays an indispensable role in further enhancing the HER activity of the whole electrocatalyst by providing extra electronic structure modulation and achieving ∆G H* optimization.…”

Rational Design of Trimetallic Sulfide Electrodes for Alkaline Water Electrolysis with Ampere‐Level Current Density

“…Although the cell voltage of Pt/C/NM k IrO 2 /NM is lower than that of NiFeMoS/NM k NiFeMoS/NM at the high work temperature of 80 °C, the durability test shows that the Pt/C/ NM k IrO 2 /NM based AEM electrolyzer degrades quite notably, suggesting that the noble metal particles were peeling off during durability test. [49,50] In contrast, the self-supporting NiFeMoS/NM electrode is almost stable under the simulated industrial environment (large current density, strong alkaline and high temperature).…”