Molybdenum-Doped Porous Cobalt Phosphide Nanosheets for Efficient Alkaline Hydrogen Evolution

Abstract

Electrocatalytic water splitting allows the production of high-purity and industrially affordable hydrogen fuel. However, the lack of highly active and robust non-noble-metal electrocatalysts has hindered the at-scale production of hydrogen for years. Here, nickel foam supported porous Mo-doped CoP nanosheets (pCoMo-P/ NF) are employed as an alkaline electrocatalyst for the hydrogen evolution reaction (HER), which was obtained from CoMoAl layered triple hydroxides (CoMoAl-LTH) derived phosphides with dissolved Al species. The unique advantage in such a synthesis process is that the introduced Mo and Al elements in the Co(OH) 2 matrix efficiently prevent the aggregation of doped CoP nanocrystals during high temperature phosphorization. Then, because of the optimized electronic structure for accelerating H* adsorption after Mo doping, as well as the increased electrochemically active surface area and decreased electrode/electrolyte interfacial resistance after dissolution of the Al species, such a pCoMo-P/NF electrocatalyst requires only 49 mV overpotential to drive 10 mA cm −2 current density in 1.0 M KOH. Additionally the electrocatalyst demonstrates prolonged stability with negligible activity decay after 3000 cycles of a cyclic voltammetry test or chronopotentiometric measurement under a static overpotential of 100 mV for 10 h. This work not only provides a synergistic strategy to design both an efficient and durable HER electrocatalyst, but also investigates the crucial elemental doping effects in phosphide electrocatalysts as well as in the transition of hydroxides to phosphides.

Chemical Modifications of Layered Double Hydroxides in the Supercapacitor

“…CoNiAl-LDH nanosheets with porous 3D sandwich-like nanostructure showing excellent electrochemical properties were vertically grown on both sides of the RGO surface. Wang et al [91] prepared ultra-large and thin sheet NiAl-LDH/reduced graphene oxide (RGO) nanocomposites via in situ growth of NiAl-LDH without any surfactant or template. The composites show ultra-large sheet-like structures and LDH nanosheets are grown evenly on the surface of the RGO, forming a homogeneous nanostructure.…”

“…In addition, some researchers have discovered that the etching of Al also generates holes, which leads to more active sites. [ 35 ] Han et al [ 82 ] synthesized Mo doped CoP on Ni foam by alkali etching and phosphorization from the CoMoAl LDH nanosheets (Figure 8g–i). Although the application of this material as a supercapacitor has not been studied, it provides a feasible way for us to realize the phase transformation of Al‐based LDHs.…”

A sulfur-doped Ni2P electrocatalyst for the hydrogen evolution reaction

“…Doping can effectively regulate their electronic structure and electronic conductivity by adjusting the chemical composition of the materials, improving their HER catalytic activity and stability. [18][19][20][21][22][23] Doped TMPs will cause charge redistribution of different components, which provides an effective means to adjust the electronic structure of the active center to improve the intrinsic activity. 24 At the same time, doping may also provide significant conductivity, large surface area and abundant active sites for the materials.…”

MOF-Derived Ultrathin Cobalt Molybdenum Phosphide Nanosheets for Efficient Electrochemical Overall Water Splitting

“…The last two bands were assigned to satellite peaks [ 28 , 29 , 30 , 48 , 49 ]. Finally, the Mo 3d XPS spectrum displayed two doublets assigned to Mo within the metal phosphide lattice (Mo 3d 5/2 = 228.2 eV) and an oxidized chemical environment (Mo 3d 5/2 = 233.0 eV) ( Figure 3 f) [ 50 , 51 , 52 ].…”