Tuning the Mn Dopant To Boost the Hydrogen Evolution Performance of CoP Nanowire Arrays

Abstract

Because of its advantages such as abundant resources, low cost, simple synthesis, and high electrochemical stability, cobalt phosphide (CoP) is considered as a promising candidate for electrocatalytic hydrogen evolution reaction. Through element doping, the morphology and electronic structure of the catalyst can be tuned, resulting in both the increase of the active site number and the improvement of the intrinsic activity of each site. Herein, we designed and fabricated Mn-doped CoP nanowires with a length of 3 μm, a diameter of 50 nm, and the pores between the grains of 10 nm. As a highly efficient electrocatalyst for alkaline hydrogen evolution, the Mn10-doped CoP/NF (doping amount is about 10 atom %) electrode presented overpotentials of 60 mV @ 10 mA cm–2 and 112 mV @ 100 mA cm–2, improved by 35 and 23%, respectively, compared with CoP/NF. Characterizations indicate that Mn doping increases the electrochemical active area, reduces the impedance, and tunes the electronic structure of the material. Density functional theory calculations also revealed that an appropriate amount of Mn dopant at a suitable location can both react as an active site itself and boost the activity of the surrounding Co sites, delivering favorable H* adsorption and rapid reaction kinetics. This result may not only promote the development of hydrogen evolution reaction catalysts but also encourage explorations of the relationship between the property and fine doping structure.

Optimizing Electronic and Geometrical Structure of Vanadium Doped Cobalt Phosphides for Enhanced Electrocatalytic Hydrogen Evolution

“…While the peaks at 781.64 eV and 797.64 eV belong to CoÀ O bond, and the peaks at 786.08 eV and 802.18 eV belong to satellite peaks. [18] Compared with CoP/NF, V doping increases the binding energy of Co 2p by 0.23 eV, which indicates that V doping reduces the external electron density of Co atoms and increases the oxidation state of Co atoms. [20,21] In the binding energies spectrum of P 2p, two peaks of at 129.19 eV and 130.09 eV belong to the 2p3/2 and 2p1/2 orbits of partial negatively charged phosphorus sites (noted as P δÀ ) because of the formation P-metal bond, respectively.…”

“…During phosphorization, the dopant leads to nanoscale imbalanced diffusion because of the diffusion ecoefficiency difference between Co and V atoms, and created abundant Kirkendall voids. Therefore, the V doped CoP had more pores and channels, and the active area of the nanowire increased significantly [18] . In order to find out the optimum doping content, the amount of different Ingredients was also investigated.…”

“…Therefore, the V doped CoP had more pores and channels, and the active area of the nanowire increased significantly. [18] In order to find out the optimum doping content, the amount of different Ingredients was also investigated. And according to the feed ratio of V and Co atoms, the samples were labeled as V 0.1 Co 0.9 P, V 0.15 Co 0.85 P, V 0.2 Co 0.8 P, V 0.3 Co 0.7 P, respectively (shown in Figure S2).…”

Nano-interfacial interactions in 2-D Ni3S2–Ni3N nanosheets for the hydrogen evolution reaction in an alkaline medium

“…However, there is a dearth of availability of such metals making them highly expensive and thus limiting their widespread use. 8 As a result, finding effective, inexpensive, and stable catalysts to meet the ever-increasing hydrogen demand is critical. In order to develop an alternative for the noble metal electrocatalysts, researchers have conducted extensive studies on non-noble metal compounds such as phosphides, [9][10][11][12] sulphides, [13][14][15][16] oxides [17][18][19][20] and nitrides.…”

In situ electrochemical construction of Co/CoP crystalline-amorphous hetero-phase catalysts for highly efficient electrocatalytic hydrogen evolution

“…7 Among these abovementioned alternatives, TMPs have gained ever-increasing interest due to their high electronic properties and superior catalytic activities derived from variable stoichiometric compositions and strong M-P covalent interactions. 8 To further boost their HER performance approaching Pt-like properties, many effective strategies, including doping, 9 introducing defects, 10 tuning compositions 11 and constructing heterogeneous structures, 12 have been extensively explored in recent years. For instance, Mn-doped CoP nanosheets prepared by electrodeposition and following annealing at high temperatures showed excellent HER catalytic activity as compared to the pristine CoP, the advantageous performance was attributed to the effective modulation for the thermo-neutral hydrogen adsorption free energy by Mn doping.…”