Synthesis of Mo-based nanostructures from organic-inorganic hybrid with enhanced electrochemical for water splitting

Abstract

scarcity and high cost of Pt severely hinder their practical application. Recently, various molybdenum-based compounds, such as MoS 2 , MoSe 2 , Mo 2 C, and MoP, are promising non-noble-metal candidates due to their comparable HER activity to Pt-based catalysts [15][16][17]. Among them, Mo 2 C, as a typical interstitial alloys material, has similar metallic structures and possesses Pt-like catalytic behaviors. The traditional synthesis method usually involves the mix of metals with carbon and subsequent carbonization under high temperature to form Mo 2 C structure, which results in serious aggregation and compromises their performance. Recently, various morphologies of Mo 2 C nanostructure with excellent HER performance have been developed through various methods [18][19][20][21][22][23]. Sun and coworkers [24] synthesized closely interconnected network of molybdenum phosphide nanostructure with highly efficient electrocatalyst for HER. Tang's group reported that nanoporous Mo 2 C can be obtained by thermal decomposition process under an inert atmosphere, which was used as a very effective electrocatalyst for generating hydrogen from water [25,26]. In addition, Sasaki's group demonstrated that small Mo 2 C nanoparticles loaded on carbon nanotubes showed highly active and durable electrocatalyst for HER [27]. Evidently, these results suggest that Mo 2 C can be used as an effective electrocatalyst for water splitting.Recently, the formation of MoO 2 with carbon materials such as graphene was used to further improve the performance of MoO 2 [28][29][30][31]. For example, Mai's group [32] synthesized ultrathin MoO 2 nanosheets encapsulated carbon matrix with a facile thermal reduction method, which showed high specific capacities and enhanced cycling stability. Li and co-workers [33] fabricated flawed MoO 2 nanobelts on graphene with enhanced HER performance. However, few reports focus on constructing heterocomposite Mo 2 C with MoO 2 . Compared with those of the corresponding homogeneous materials, these heterostructured A simple method to fabricate Mo-based nanostructures were developed by the thermal decomposition of MoOx-based organic-inorganic hybrid nanowires. Well-defined Mo-based nanostructures, including MoO2 and MoO3 nanowires, can be prepared by changing the hybrid precursor. More importantly, Mo2C/MoO2 heterostructures with porous structure were successfully synthesized under an inert atmosphere. The resultant Mo2C/ MoO2 heterostructures show enhanced electrocatalytic activity and superior stability for electrochemical hydrogen evolution from water. The enhanced performance might be ascribed to the high electrical conductivity and porous structures with one-dimensional structure. Indeed, our result described here provides a new way to synthesize other Mo-based nanostructures for various applications.

Cobalt-vanadium bimetal-based nanoplates for efficient overall water splitting

“…Among them, the Co/VN shows a small onset potential of 62 mV (vs. RHE, all the potentials are referenced to RHE in this work). At a current density of 10 mA cm −2 , Co/VN gives an overpotential of only 92 mV, which is much lower than that of common HER electrocatalysts, such as Co-N-MoO 2 (258 mV) [35], VS/Ni x S y /NF (233 mV) [44], VC-NS (98 mV) [38], CoS 2 /MoS 2 /RGO (160 mV) [56] and Mo 2 C/ MoO 2 (315 mV) [57]. For Co 2 VO 4 and Co 3 V/VN, the overpotentials required to reach the current density of 10 mA cm −2 are about 205 and 136 mV, being worse than that of Co/VN.…”

Facile synthesis and excellent electrochemical performance of CoP nanowire on carbon cloth as bifunctional electrode for hydrogen evolution reaction and supercapacitor

“…The performance of supercapacitor and electrocatalysts for HER has been improved by the development of nanomaterials with various nanostructures, such as nanowires, nanoparticles, and nanosheets [21,24,28,29]. Furthermore, flexible electrodes will play an important role for electrocatalysts in flexible water splitting devices and supercapacitors in flexible electronic devices [19,24,30].…”

Acid promoted Ni/NiO monolithic electrode for overall water splitting in alkaline medium

“…However, the most efficient noble-metal based electrocatalysts suffer from natural resource scarcity and high-cost, which hampers their broad utilization [7][8][9][10]. Although a variety of non-noble metal-based nanostructured materials such as Mo 2 C/MoO 2 [11], Co 9 S 8 /graphene [12], CoPS [13], CoMoS [14], NiMoN [15] have been reported, the facts are still far from satisfactory since these materials are either for oxygen evolution reaction (OER) catalysts working in strongly alkaline conditions or for hydrogen evolution reaction (HER) catalysts operating in strongly acidic mediums due to the thermodynamic convenience [5,[16][17][18]. The inferior efficiency caused by the disparity of the stability and activity for the same catalyst system in the operating pH ranges [19,20] limits the practical implementations of these materials as a catalytic electrode in an integrated electrolyser.…”