Stacked Porous Iron-Doped Nickel Cobalt Phosphide Nanoparticle: An Efficient and Stable Water Splitting Electrocatalyst

Exploration of proficient electrocatalyst from earth-abundant nonprecious metals in lieu of noble metal-based catalysts to obtain clean hydrogen energy through large-scale electrochemical water splitting is still an ongoing challenge. Herein, iron-doped nickel cobalt phosphide nanoplate arrays grown on a carbon cloth (NiCoFe_<i>x</i>P/CC) are fabricated using a simple hydrothermal route, followed by phosphorization. The electrochemical analysis demonstrates that the NiCoFe_<i>x</i>P/CC electrode possesses high electrocatalytic activity for water splitting in alkaline medium. Benefits from the synergistic effect between the metal centers, two-dimensional porous nanoplates, and unique three-dimensional electrode configuration of NiCoFe_<i>x</i>P/CC provide small overpotentials of 39 at 10 mA cm^–2 and 275 mV at 50 mA cm^–2 to drive the hydrogen evolution reaction and oxygen evolution reaction, respectively. Furthermore, the assembled two-electrode (NiCoFe_<i>x</i>P/CC∥NiCoFe_<i>x</i>P/CC) alkaline water electrolyzer can achieve 10 mA cm^–2 current density at 1.51 V. Remarkably, it can maintain stable electrolysis over 150 h. The excellent activity and stability of this catalyst is proved to be a economical substitute of commercial noble metal-based catalysts in technologies relevant to renewable energy

Amorphous Phosphorus-Incorporated Cobalt Molybdenum Sulfide on Carbon Cloth: An Efficient and Stable Electrocatalyst for Enhanced Overall Water Splitting over Entire pH Values

The development of economical, proficient, and highly stable catalysts to substitute the expensive noble metal electrodes for electrocatalytic water-splitting applications is exceedingly desirable. In this context, the most fascinating and challenging approach is the rational design of a nanocomposite encompassing multiple components with unique functionalities. Herein, we describe the fabrication of a strongly catalytic and superb durable phosphorus-incorporated cobalt molybdenum sulfide electrocatalyst grown on carbon cloth (P-CoMoS/CC). The hybrid material exhibited excellent activity for hydrogen and oxygen evolution reactions over a wide range of pH (1–14) with extremely high stability (∼90% retention of the initial current density) after 24 h of electrolysis. Importantly, when P-CoMoS/CC was used as both cathode and anode for overall water splitting, a very low cell voltage of 1.54 V is required to attain the 10 mA cm^–2 current density, and the hybrid material exhibited a long-term stability (89.8% activity retention after 100 h). The outstanding overall water-splitting performance compared to an electrolyzer consisting of the noble-metal-based catalysts Pt/C and RuO₂ makes P-CoMoS one of the most efficient earth-abundant water-splitting catalysts. Phosphorus incorporation was proved to be a vital aspect for the improved charge-transfer properties and catalytic durability of the P-CoMoS/CC catalyst

Enhanced Supercapacitive Performance of Chemically Grown Cobalt–Nickel Hydroxides on Three-Dimensional Graphene Foam Electrodes

Chemical growth of mixed cobalt–nickel hydroxides (Co_<i>x</i>Ni_1–<i>x</i>(OH)₂), decorated on graphene foam (GF) with desirable three-dimensional (3D) interconnected porous structure as electrode and its potential energy storage application is discussed. The nanostructured Co_<i>x</i>Ni_1–<i>x</i>(OH)₂ films with different Ni:Co (<i>x</i>) compositions on GF are prepared by using the chemical bath deposition (CBD) method. The structural studies (X-ray diffraction and X-ray photoelectron spectroscopy) of electrodes confirm crystalline nature of Co_<i>x</i>Ni_1–<i>x</i>(OH)₂/GF and crystal structure consists of Ni­(OH)₂ and Co­(OH)₂. The morphological properties reveal that nanorods of Co­(OH)₂ reduce in size with increases in nickel content and are converted into Ni­(OH)₂ nanoparticles. The electrochemical performance reveals that the Co_0.66Ni_0.33(OH)₂/GF electrode has maximum specific capacitance of ∼1847 F g^–1 in 1 M KOH within a potential window 0 to 0.5 V vs Ag/AgCl at a discharge current density of 5 A g^–1. The superior pseudoelectrochemical properties of cobalt and nickel are combined and synergistically reinforced with high surface area offered by a conducting, porous 3D graphene framework, which stimulates effective utilization of redox characteristics and communally improves electrochemical performance with charge transport and storage