MOF-on-MOF Strategy to Construct a Nitrogen-Doped Carbon-Incorporated CoP@Fe–CoP Core-Shelled Heterostructure for High-Performance Overall Water Splitting

Abstract

The design and preparation of efficient and low-cost catalysts for water electrolysis are crucial and highly desirable to produce eco-friendly and sustainable hydrogen fuel. Herein, we prepared nitrogen-doped carbon-incorporated CoP@Fe–CoP core-shelled nanorod arrays grown on Ni foam (CoP@Fe–CoP/NC/NF) through phosphorization of ZIF-67@Co–Fe Prussian blue analogue (ZIF-67@CoFe–PBA). The hierarchical nanorod arrays combined with the core-shelled structure offer favorable mass/electron transport capacity and maximize the active sites, thus enhancing the electrochemically active surface area. The synergistic effect of the bimetallic components and the nitrogen-doped carbon matrix endow the composite with an optimized electronic structure. Benefiting from the above superiorities of morphological and chemical compositions, this self-supported CoP@Fe–CoP/NC/NF heterostructure can drive alkaline hydrogen evolution reaction and oxygen evolution reaction with overpotentials of 97 and 270 mV to yield 100 mA cm–2, respectively. The two-electrode alkaline electrolyzer constructed by this heterostructure shows a low cell voltage of 1.58 V to yield 10 mA cm–2, superior to the precious-metal-based electrocatalyst apparatus (IrO2∥Pt/C). This study offers a feasible and facile approach to develop efficient electrocatalysts for water electrolysis, which applies to other electrochemical energy conversion and storage applications.

MOF-derived carbon-coated cuprous phosphide nanosheets for electrocatalytic glucose oxidation

“…5b shows the CV curves at a fixed scan rate of 50 mV s −1 , in which the anode peak currents increase significantly after continuously adding the glucose concentration in the range of 0 to 4 mM on account of the excellent electrocatalytic oxidation activity. 30,31 Through electrochemical impedance spectroscopy (EIS), it is not difficult to find that the impedance for the phosphatized sample of Cu-BTC-CP is lower than the carbonized Cu-BTC-C with a larger slope value within the low-frequency region (Fig. 5c).…”

FeP-CoP Nanocubes In Situ Grown on Ti3C2Tx MXene as Efficient Electrocatalysts for the Oxygen Evolution Reaction

“…The peaks at 778.36 and 793.26 eV are assigned to the Co 2+ 2p 3/2 and 2p 1/2 of Co−P bonds, and the peaks with binding energies of 781.57 and 797.57 eV are attributed to the oxidized Co 3+ species owing to the surface oxidation. 39,40 Notably, compared with the FeP-CoP, both the doublets belonging to Fe−P and Co−P of the FeP-CoP/Ti 3 C 2 T x -5 shift negatively, suggesting the strong coupling interaction between FeP-CoP and Ti 3 C 2 T x MXene. 41,42 Meanwhile, the peaks indexed to oxide species of Fe and Co become more obvious for FeP-CoP/Ti 3 C 2 T x -5, owing to the surface oxidation of phosphides with a smaller size.…”

Synergistically Coupling of Manganese-Doped CoP Nanowires Arrays with Highly Dispersed Ni(PO3)2 Nanoclusters toward Efficient Overall Water Splitting

“…In order to overcome the above intrinsic defects of Co-based phosphides, it has been a common strategy to introduce second or third phase metal elements to construct bimetallic or trimetallic phosphides. It is reported that the introduction of second or third phase metal elements (such as Fe, Ni, Mo, Cu, Mn, and so on) can effectively optimize surface electronic structure of Co-based phosphides and expose them to more active centers, which will improve their inherent electrocatalytic activity. − For example, it was shown that an Fe-doped CoP nanoarray exhibited outstanding HER and OER performance, which further facilitated showing that it exhibited a low cell voltage of 1.60 V to drive an overall water-splitting current of 10 mA/cm 2 in a symmetrical two electrode system . Among various metal elements for the doping of Co-based phosphides, manganese (Mn) is particularly promising because of its extremely higher electronegativity compared with most of the common metal elements, which can greatly promote electronic transmission and tailor the electronic structure. − However, due to the limitation of active site exposure and charge transfer capacity, their electrocatalytic performances are still not ideal, especially in overall water splitting.…”

“…In addition to the doping of metal elements, constructing a heterogeneous interface by integration of different catalysts into a multiphase core–shell structure is another effective means to improve the electrocatalytic performance of Co-based phosphide catalysts. ,− It was shown that abundant heterogeneous interfaces not only can expose more reactive sites and accelerate the electron transport rate but also can realize synchronous adsorption of reaction intermediates. For instance, it was shown that CoP/NiCoP hybrid nanosheet networks exhibited outstanding HER activity with an ultralow overpotential of 75 mV to deliver a current density of 10 mA/cm 2 .…”