CoP₂/Co₂P Encapsulated in Carbon Nanotube Arrays to Construct Self-Supported Electrodes for Overall Electrochemical Water Splitting

Abstract

Electrocatalytic water splitting is a desirable and sustainable strategy for hydrogen production yet still faces challenges due to the sluggish kinetics and rapid deactivation of catalysts in the oxygen evolution process. Herein, we utilized the metal-catalyzed growth technology and phosphating process to fabricate self-supported electrodes (Co x P y @CNT-CC) composed of carbon nanotube (CNT) arrays grown on carbon cloth (CC); thereinto, cobalt-based phosphide nanoparticles (Co x P y ) are uniformly encapsulated in the cavity of the CNTs. After further optimization, when the nanoparticles are in the composite phase (CoP 2 /Co 2 P), CoP 2 /Co 2 P@CNT-CC served as catalytic electrodes with the highest activity and stability for electrocatalytic water splitting in an alkaline medium (1.0 M KOH). The as-prepared CoP 2 /Co 2 P@CNT-CC integrates the advantages of the abundant active sites and confinement effect of CNTs, imparting promising electrocatalytic activities and stability in catalyzing both hydrogen evolution reaction and oxygen evolution reaction. Remarkably, electrocatalytic water splitting cells assembled using CoP 2 /Co 2 P@CNT-CC electrodes as the cathode and anode, respectively, require a cell voltage of 1.55 V at 10 mA cm −2 , which is lower than that of the commercially noble Pt/C/CC and RuO 2 /CC catalyst couple (1.68 V). Besides, a CoP 2 /Co 2 P@CNT-CC||CoP 2 /Co 2 P@CNT-CC system shows outstanding durability for a period of 100 h at 10 mA cm −2 . This work may provide new ideas for designing bifunctional electrocatalysts for applications in electrocatalytic water splitting.

Ultrathin NiFe-Based Nanosheet Electrocatalysts for Efficient Water Oxidation

“…Ideal electrocatalysts for water splitting have been eagerly pursued, and they should exhibit good electronic conductivity, high active areas, rich active sites, and long-term stability and have simple synthesis and low prices . Nonnoble transition metal alloys and their derivatives, such as oxides, − nitrides, , phosphides, , selenides, − and sulfides, , exhibit good OER or hydrogen evolution reaction (HER) properties. Especially, Ni-based materials have attracted a lot of attention owing to their low cost, abundant reserves, and good corrosion resistance in alkaline solutions .…”

Interface-Modified Ni–Fe–P/Co–P/NF Alloys for Electrocatalytic Water Splitting in Alkaline Solution

“…With the increasing environmental concern and energy crisis, there is an urgent demand for clean, renewable, and sustainable energies, such as hydrogen energy and nuclear energy. Water splitting through electrolysis is recognized as a promising solution to obtain hydrogen and oxygen as a result of accessible raw material and zero carbon footprints, − thus further advancing some sustainable and renewable energy conversion and storage systems. However, the overpotential originating from the electrode polarization leads to a wider voltage window than the theoretical value (1.23 V) to afford a thermodynamic driving force .…”

Synergistically Regulating the Electronic Structure of CoS by Cation and Anion Dual‐Doping for Efficient Overall Water Splitting

“…[21][22][23][24][25] Recently, a series of transition metals-based materials (mainly Co, Ni, Mn, Fe, and Mo) have attracted attention for their cost-effectiveness, great flexibility in terms of structure and morphology and high stability, and their efficiency can be comparable to those of precious metals including platinum, iridium and rhodium. [26] Among them, metal oxide, [27][28][29][30][31] carbide, [32] sulfide, [33,34] phosphide, [35][36][37] nitride [38,39] and selenide [40] have been often used for efficient water oxidation. Surprisingly, transition metal sulfides (TMSs) are taken for a valuable noble metal-free electrocatalyst because of their high conductivity and ideal atomic arrangement.…”