Bifunctionality from Synergy: CoP Nanoparticles Embedded in Amorphous CoOx Nanoplates with Heterostructures for Highly Efficient Water Electrolysis

Abstract

Hydrogen production from renewable electricity relies upon the development of an efficient alkaline water electrolysis device and, ultimately, upon the availability of low cost and stable electrocatalysts that can promote oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Normally, different electrocatalysts are applied for HER and OER because of their different reaction intermediates and mechanisms. Here, the synthesis of a heterostructured CoP@a‐CoOx plate, which constitutes the embedded crystalline cobalt phosphide (CoP) nanoclusters and amorphous cobalt oxides (CoOx) nanoplates matrix, via a combined solvothermal and low temperature phosphidation route is reported. Due to the presence of synergistic effect between CoP nanoclusters and amorphous CoOx nanoplates in the catalyst, created from the strong nanointerfaces electronic interactions between CoP and CoOx phases in its heterostructure, this composite displays very high OER activity in addition to favorable HER activity that is comparable to the performance of the IrO2 OER benchmark and approached that of the Pt/C HER benchmark. More importantly, an efficient and stable alkaline water electrolysis operation is achieved using CoP@a‐CoOx plate as both cathode and anode as evidenced by the obtainment of a relatively low potential of 1.660 V at a 10 mA cm−2 current density and its marginal increase above 1.660 V over 30 h continuous operation.

Channel‐Rich RuCu Nanosheets for pH‐Universal Overall Water Splitting Electrocatalysis

“…Lattice spacing is measured to be 0.23 nm, corresponding to the (100) facet of Ru and no lattice fringe of Cu is observed (Figure 1g). [26,27] To optimize the catalytic performance,t he channel-rich RuCu NSs were loaded on carbon black (Supporting In-formation, Figure S4) and annealed in air for 1hat different temperatures (that is,2 50 8 8C, 300 8 8Ca nd 350 8 8C, denoted as RuCu NSs/C-T, T = 250 8 8C, 300 8 8C, 350 8 8C, respectively) (Supporting Information, Figure S5). All the results indicate that RuCu NSs are composed of crystallized Ru and amorphous Cu.…”

Silica‐Free Synthesis of Mesoporous Co3O4/CoOxPy as a Highly Active Oxygen Evolution Reaction Catalyst

“…To further evaluate its potential application value, we compared the overpotential of M−Co 3 O 4 /CoO x P y with other reported Co‐based catalysts as listed in Table S1. We show that the OER activity of M−Co 3 O 4 /CoO x P y is comparable, if not better than most of the Co‐based materials including a few CoP catalyst, suggesting the synergistic effect between the heterogeneous Co 3 O 4 /CoO x P y structure and possibly also among the mixed CoO, Co 2 P and CoP species . Figure b shows the corresponding Tafel plot, where the potentials are plot versus the logarithm of current density .…”

“…The M−Co 3 O 4 /CoO x P y showed a higher C dl of 8.1 mF cm −2 and a larger electrochemical active surface areas (ECSA) of 39.1 cm 2 compared with these of M−Co 3 O 4 (5.1 mF cm −2 and 24.6 cm 2 ), despite of its lower specific surface area. The result suggested that there are more active sites on the surface of M−Co 3 O 4 /CoO x P y , possibly derived from the heterogeneous structure and the synergistic effect between Co 3 O 4 and CoO x P y . The charge‐transfer in both catalysts were also studied using electrochemical impedance spectroscopy (EIS) as shown in Figure d.…”

CoP‐Doped MOF‐Based Electrocatalyst for pH‐Universal Hydrogen Evolution Reaction

“…The other peaks in Co 2p 3/2 of CoP correspond to Co 3+ /Co 2+ (780.7 eV,7 82.5 eV) and satellite peaks (784.5 eV). [5c] In addition, OÀCo (531.2 eV) and OÀC( 532.1 eV) peaks can be seen in all the samples, [13] and the O À P (533.1 eV) peak is observed in CoP/Co-MOF and CoP. N À Co and N À Hp eaks are both observed in Co-MOF and CoP/Co-MOF, [12] while the N À Ppeak is only found in CoP/Co-MOF due to the partial phosphorization process.…”