Constructing Carbon-Encapsulated NiFeV-Based Electrocatalysts by Alkoxide-Based Self-Template Method for Oxygen Evolution Reaction

Abstract

The development of green and sustainable water-splitting hydrogen production technology is beneficial to reducing the over-reliance on fossil fuels and realizing the strategic goal of "carbon neutral". As one of the half reactions for water splitting, oxygen evolution reaction has suffered the problems of sluggish four-electron transfer process and relatively slow reaction kinetics. Therefore, exploring efficient and stable catalysts for oxygen evolution reaction is of critical importance for water-splitting technology. Metal alkoxides are a series of compounds formed by the coordination function of metal ions with alcohol molecules. Metal alkoxides possess the double advantages of organic materials and inorganic materials, which makes them reveal a promising application in the electrochemical field. In view of the poor activity and stability of the current oxygen evolution reaction electrocatalysts, this study has adopted the alkoxide-based self-template method to prepare the carbon-encapsulated NiFeV-based electrocatalysts through using the solid NiFeV-alkoxides as precursors. The organic components in solid metal alkoxides are employed to achieve the graphitized carbon encapsulation after the high-temperature calcination process, which is beneficial for improving the conductivity and corrosion resistance of catalysts. Through adjusting the V doping amounts and the calcination temperatures, the electronic structure of NiFe nanoparticles and carbon encapsulation were optimized, which are both key influence factors for oxygen evolution performances. As a result, the oxygen evolution catalysts with high activity and stability were obtained successfully in this work. The experimental results have shown that the NiFeV-based catalysts presented a uniform spherical structure with carbon encapsulation. The current density of 20 mA·cm^-2 could be obtained at the overpotential of only 381 mV as an electrocatalyst for oxygen evolution reaction in water electrolysis. After the continuous 10000 s durability test, the NiFeV-based catalyst exhibited slight reduction in current density but still maintained the catalytic activity almost similar to the initial one, revealing a good oxygen evolution stability. The excellent catalytic activity and stability of NiFeV-based catalysts are believed to be mainly attributed to the uniform spherical structure, the optimized regulation of V on the electronic structure and the protective effect of carbon encapsulation on metal particles. The V element in the catalysts exhibited the rich redox states of V³⁺, V⁴⁺ and V⁵⁺, which can effectively adjust the electronic structure of adjacent atoms and optimize the binding energy of oxygen reduction reaction intermediates, thus improving the electrocatalytic performance of catalysts. This work provides a useful guidance for improving the electrocatalytic performance of oxygen evolution catalysts through the V-doping and carbon encapsulation strategies.

Keywords

Oxygen evolution catalyst / Solid metal alkoxides / High-temperature calcination / Carbon encapsulation / V-doping

References

[1] Long X, Li J K, Xiao S, Yan K Y, Wang Z L, Chen H N, Yang S H. A strongly coupled graphene and FeNi double hydroxide hybrid as an excellent electrocatalyst for the oxygen evolution reaction[J]. Angew. Chem. Int. Ed., 2014, 53(29): 7584-7588.

[2] Wang L, Zhou Q, Pu Z H, Zhang Q, Mu X Q, Jing H Y, Liu S L, Chen C Y, Mu S C. Surface reconstruction engineering of cobalt phosphides by Ru inducement to form hollow Ru-RuPx-CoxP pre-electrocatalysts with accelerated oxygen evolution reaction[J]. Nano Energy, 2018, 53: 270-276.

[3] Bai Z Y, Qin J, Zhang Y, Yuan Y. Design and synthesis of pomegranate-like Co₃O₄@ZIF-8 nano-electrocatalysts for oxygen reduction/evolution reactions[J]. J. Henan Normal U(Nat Sci Ed)., 2021, 49(04): 60-67.

[4] Wu Z X, Wang J, Guo J B, Zhu J, Wang D L. Research progress of molybdenum-based electrocatalysts for hydrogen evolution reaction[J]. J. Electrochem., 2016, 22(2): 192-204.

[5] Xuan C J, Wang J, Zhu J, Wang D L. Recent progress of metal organic frameworks-based nanomaterials for electrocatalysis[J]. Acta Phys-Chim Sin., 2017, 1: 149-164.

[6] Rosalbino F, Scavino G, Actis Grande M. Electrocatalytic activity of Ni-Fe-M (M=Cr, Mn, Cu) sintered electrodes for hydrogen evolution reaction in alkaline solution[J]. J. Electrochem., 2013, 694: 114-121.

[7] Wang P Y, Pu Z H, Li W Q, Zhu J W, Zhang C T, Zhao Y F, Mu S C. Coupling NiSe₂-Ni₂P heterostructure nanowrinkles for highly efficient overall water splitting[J]. J Catal., 2019, 377: 600-608.

[8] Kou Z K, Wang T T, Pu Z H, Wu L, Xi K, Mu S C. Realizing the extraction of carbon from WC for in situ formation of W/WC heterostructures with efficient photoelectrochemical hydrogen evolution[J]. Nanoscale Horiz., 2019, 4(1): 196-201.

[9] Zhong D Z, Liu L, Li D D, Wei C C, Wang Q, Hao G Y, Zhao Q, Li J P. Facile and fast fabrication of iron-phosphate supported on nickel foam as a highly efficient and stable oxygen evolution catalyst[J]. J. Mater. Chem. A, 2017, 5(35): 18627-18633.

[10] Wang Z Q, Liu W H, Geng F X. Progress in research of transition metal layered double hydroxide electrocatalysis[J]. Materials China., 2017, 36(9): 659-666.

[11] Gao R, Yan D P. Recent development of Ni/Fe-based micro/nanostructures toward photo/electrochemical water oxidation[J]. Adv. Energy Mater., 2019: 1900954.

[12] Li P S, Duan X X, Kuang Y, Li Y P, Zhang G X, Liu W, Sun X M. Tuning electronic structure of NiFe layered double hydroxides with vanadium doping toward high efficient electrocatalytic water oxidation[J]. Adv. Energy Mater., 2018, 8(15): 703341.

[13] Jiang J, Sun F F, Zhou S, Hu W, Zhang H, Dong J C, Jiang Z, Zhao J J, Li J F, Yan W S, Wang M. Atomic-level insight into super-efficient electrocatalytic oxygen evolution on iron and vanadium co-doped nickel (oxy)hydroxide[J]. Nat. Commun., 2018, 9(1): 2885.

[14] Majeed A, Hou P X, Zhang F, Tabassum H, Li X, Li G X, Liu C, Cheng H M. A freestanding single-wall carbon nanotube film decorated with N-doped carbon-encapsulated Ni nanoparticles as a bifunctional electrocatalyst for overall water splitting[J]. Adv. Sci., 2019, 6(12): 1802177.

[15] Zhu J B, Xiao M L, Zhang Y L, Jin Z, Peng Z Q, Liu C P, Chen S L, Ge J J, Xing W. Metal-organic framework-induced synthesis of ultrasmall encased NiFe nanoparticles coupling with graphene as an efficient oxygen electrode for a rechargeable Zn-air battery[J]. ACS Catal., 2016, 6(10): 6335-6342.

[16] Cui X J, Ren P J, Deng D H, Deng J, Bao X H. Single layer graphene encapsulating non-precious metals as high-performance electrocatalysts for water oxidation[J]. Energy Environ. Sci., 2016, 9(1): 123-129.

[17] Lee E, Park A H, Park H U, Kwon Y U. Facile sonochemical synthesis of amorphous NiFe-(oxy)hydroxide nanoparticles as superior electrocatalysts for oxygen evolution reaction[J]. Ultrason. Sonochem., 2018, 40: 552-557.

[18] Wang M, Jiang J, Ai L H. Layered bimetallic iron-nickel alkoxide microspheres as high-performance electrocatalysts for oxygen evolution reaction in alkaline media[J]. ACS Sustain. Chem. Eng., 2018, 6(5): 6117-6125.

[19] Liu X P, Deng S F, Liu P F, Liang J N, Gong M X, Lai C L, Lu Y, Zhao T H, Wang D L. Facile self-template fabrication of hierarchical nickel-cobalt phosphide hollow nanoflowers with enhanced hydrogen generation performance[J]. Sci. Bull., 2019, 64(22): 1675-1684.

[20] Zhao J, Zou Y C, Zou X X, Bai T Y, Liu Y P, Gao R Q, Wang D J, Li G D. Self-template construction of hollow Co₃O₄microspheres from porous ultrathin nanosheets and efficient noble metal-free water oxidation catalysts[J]. Nanoscale, 2014, 6(13): 7255-7262.

[21] Ma F X, Xu C Y, Lyu F C, Song B, Sun S C, Li Y Y, Lu J, Zhen L. Construction of FeP hollow nanoparticles densely encapsulated in carbon nanosheet frameworks for efficient and durable electrocatalytic hydrogen production[J]. Adv. Sci., 2019, 6(3): 1801490.

[22] Yu L, Xia B Y, Wang X, Lou X W. General formation of M-MoS₃ (M=Co, Ni) hollow structures with enhanced electrocatalytic activity for hydrogen evolution[J]. Adv. Mater., 2016, 28(1): 92-97.

[23] Liu H, Ma F X, Xu C Y, Yang L, Du Y, Wang P P, Yang S, Zhen L. Sulfurizing-induced hollowing of Co₉S₈microplates with nanosheet units for highly efficient water oxidation[J]. ACS Appl. Mater. Interfaces, 2017, 9(13): 11634-11641.

[24] Feng X T, Jiao Q Z, Liu T, Li Q, Yin M M, Zhao Y, Li H S, Feng C H, Zhou W. Facile synthesis of Co₉S₈hollow spheres as a high-performance electrocatalyst for the oxygen evolution reaction[J]. ACS Sustain. Chem. Eng., 2017, 6(2): 1863-1871.

[25] Liu X P, Gong M X, Deng S F, Zhao T H, Zhang J, Wang D L. Recent advances on metal alkoxide based electrocatalysts for water splitting[J]. J. Mater. Chem. A, 2020, 8(20): 10130-10149.

[26] Liu X P, Deng S F, Xiao D D, Gong M X, Liang J N, Zhao T H, Shen T, Wang D L. Hierarchical bimetallic Ni-Co-P microflowers with ultrathin nanosheet arrays for efficient hydrogen evolution reaction over all pH values[J]. ACS Appl. Mater. Interfaces, 2019, 11(45): 42233-42242.

[27] Wang J M, Ma X, Qu F L, Asiri A M, Sun X P. Fe-doped Ni₂P nanosheet array for high-efficiency electrochemical water oxidation[J]. Inorg. Chem., 2017, 56(3): 1041-1044.

[28] Yu Y, Li P, Wang X F, Gao W Y, Shen Z X, Zhu Y N, Yang S L, Song W G, Ding K J. Vanadium nanobelts coated nickel foam 3D bifunctional electrode with excellent catalytic activity and stability for water electrolysis[J]. Nanoscale, 2016, 8(20): 10731-10738.