Synergistic Interfacial Engineering of Heterostructured Cobalt Phosphide Spheres/Cobalt Hydroxide Nanosheets for Overall Water Splitting

Abstract

Recently, transition metal phosphides (TMPs) have been widely explored for the hydrogen evolution reaction (HER) due to their advantaged activity. Nevertheless, the OER performance of TMPs in an alkaline medium is still unsatisfactory. Therefore, interfacial engineering of TMPs to enhance the OER performance is highly desirable. Herein, a Co(OH) 2 nanosheet coupled with a CoP sphere supported on nickel foam (NF) is developed by a simple two-step electrodeposition. The large surface area derived from stacked nanosheets and the electronic regulation induced by heterostructure can significantly enhance charge/mass transfer and expose more active sites, thus accelerating the kinetics of the reaction. In addition, the strong electronic interaction between CoP and Co(OH) 2 is conducive to the generation of a high valence cobalt center; thus, the electrocatalytic performances toward HER and OER are remarkably improved. Impressively, the optimized CoP/Co(OH) 2 @NF heterostructure obtains an excellent HER and OER performance with low overpotentials of 76 and 266 mV at 10 mA cm −2 , respectively, superior to the commercial Pt/C and RuO 2 . Moreover, the optimized CoP/Co(OH) 2 @NF can afford the lowest cell voltage of 1.58 V to achieve 10 mA cm −2 for alkaline overall water splitting and shows outstanding longterm stability.

Rational Design of CoOOH/α-Fe2O3/SnO2 for Boosted Photoelectrochemical Water Oxidation: The Roles of Underneath SnO2 and Surface CoOOH

“…OEC not only plays important roles that traps and stores photogenerated holes but also acts as catalytic active sites for the OER. In this field, many transition metal (Ni, Co, and Fe)-based phosphate complexes, (oxy) hydroxides, and layered double hydroxides have been extensively explored. − For example, cobalt (oxy)­hydroxide (CoOOH) exhibits outstanding PEC OER activity in the systems like CoOOH/TiO 2 , CoOOH/P:Fe 2 O 3 , CoOOH/BiVO 4 , and CoOOH/Ta 3 N 5 . − Especially, our previous studies indicated that CoOOH is inclined to promote holes transfer/trapping, thus increase the effective charge separation . However, the PEC performance of the α-Fe 2 O 3 -based photoelectrode still requires further promotion to meet the practical application.…”

Morphological control and performance engineering of Co-based materials for supercapacitors

“…4 Therefore, in order to use the electricity produced by wind and solar energy more efficiently, electrochemical storage technology is urgently needed. 5,6 At present, the most advanced electrochemical energy-storage technology can be classified into two major categories: lithium-ion batteries and supercapacitors. 7–10 Compared with lithium-ion batteries, supercapacitors exhibit many advantages such as higher power density, faster charge–discharge speed and longer cycle-life, 11–14 as illustrated in Fig.…”