RESUMEN
Manipulating metal valence states and porosity in the metal-organic framework (MOF) by alloying has been a unique tool for creating high-valent metal sites and pore environments in a structure that are inaccessible by other methods, favorable for accelerating the catalytic activity towards sensing applications. Herein, we report Fe3+-driven formation of catalytic active Ni3+ species in the amine-crafted benzene-dicarboxylate (BDC-NH2)-based MOF as a high-performance electrocatalyst for glucose sensing. This work took the benefit of different bonding stability between BDC-NH2 ligand, and Fe3+ and Ni2+ metal precursor ions in the heterometallic NixFe(1-x)-BDC-NH2 MOF. The FeCl3 that interacts weakly with ligand, oxidizes the Ni2+ precursor to Ni3+-based MOF owing to its Lewis acidic behavior and was subsequently removed from the structure supported by Ni atoms, during solvothermal synthesis. This enables to create mesopores within a highly stable Ni-MOF structure with optimal feed composition of Ni0.7Fe0.3-BDC-NH2. The Ni3+-based Ni0.7Fe0.3-BDC-NH2 demonstrates superior catalytic properties towards glucose sensing with a high sensitivity of 13,435 µA mM-1 cm-2 compared to the parent Ni2+-based Ni-BDC-NH2 (10897 µA mM-1cm-2), along with low detection limit (0.9 µM), short response time (≤5 s), excellent selectivity, and higher stability. This presented approach for fabricating high-valent nickel species, with a controlled quantity of Fe3+ integrated into the structure allowing pore engineering of MOFs, opens new avenues for designing high-performing MOF catalysts with porous framework for sensing applications.
RESUMEN
Designing two-dimensional (2D) heterostructures based on suitable energy materials is a promising strategy to achieve high-performance supercapacitors with hybridized transition metal and carbonaceous-based electrodes. The influence of each component and its content on the capacitor performance necessitates deeper insights. In this study, a 2D/2D heterostructure made of hierarchical pseudocapacitive cobalt phosphide/oxide and P-doped reduced graphene oxide (PrGO) nanosheets (CoP/CoO@PrGO) was fabricated using porous zeolitic-imidazolate framework precursor. The decoration of 2D leaf-like CoP/CoO hybrid onto PrGO could create a unique interface with a large number of active sites, CoO-driven creation of pseudocapacitive surface POx species, and high P content (â¼3 at.%) in PrGO, thus promoting the Faradaic reaction, electrical conductivity, and overall charge storage. This framework yields a high specific capacitance of 405 F g-1 at 5 A g-1 and excellent cycling stability (over 100 % after 10,000 cycles), superior to those of pristine CoP@PrGO (300 F g-1 at 5 A g-1). Furthermore, the fabricated asymmetric supercapacitor delivers reasonable energy density of 4.2 Wh kg-1 at a power density of 785 W kg-1 and cycling stability of â¼100 % after 10,000 cycles. Therefore, CoP/CoO@PrGO with its unique interfacial properties can promote the development of heterostructure electrode for high-performance supercapacitors.
RESUMEN
Echinops-like bimetallic CoNiP-CoNi alloy is synthesized from a metal-organic framework (MOF) and serves as an efficient catalyst for the oxygen evolution reaction (OER), with a low overpotential of 300â mV in 1â M KOH at 10â mA cm-2 (η10 ). The cooperative effect of Ni and Co metal, as well as the interfacial properties of the integrated semiconducting phosphide/metallic alloy and electronic conductivity of the MOF-derived carbon regulate the performance of the catalyst. Moreover, the bimetallic CoNiP/CoNi alloy catalyst is interspersed with N-doped graphene, forming a triad catalyst that demonstrates superior activity towards the hydrogen evolution reaction (η10 =150â mV) and excellent durability, owing to interfacial effects of the triad catalyst, large electrochemical active surface area, and enhanced conductivity from N-doped graphene. The stability of the carbon-containing catalyst during OER (oxidation) is altered by the high reactivity of heteroatom dopant. The assembled CoNiP/CoNi/N-RGO||CoNiP/CoNi water electrolyzer delivers a reasonable cell potential of 1.76â V at 10â mA cm-2 . The synthesized bimetallic CoNiP/CoNi alloy-based triad catalyst thus demonstrates excellent electrocatalytic activity and high durability suitable for efficient alkaline water splitting.
RESUMEN
The fabrication of interpenetrated heterostructures from desirable energy materials for the development of efficient supercapacitors is promising yet challenging. Herein, a leaf-shaped cobalt phosphide/cobalt oxide heterostructure, (CoPx)1-y/CoOy (0.44 > y > 0.06), was synthesized from 2D-zeolitic-imidazolate-framework (ZIF-Co-L) molecular precursor via phosphidation of the Co3O4 intermediate. The efficient construction of heterostructure through the variation of surface/bulk composition significantly alters the interfacial properties and electronic structure, yielding enhanced supercapacitor performance. Further, gas-phase phosphidation entails a core-shell formation mechanism via gas diffusion, regulated by the Kirkendall effect. The optimized heterostructure (y = 0.10) exhibits remarkable interfacial properties derived from the CoO/Co0/CoP interface, thus facilitating a high specific capacitance (467 F g-1 at 5 A g-1) and excellent cycling stability (~91% after 10000 cycles) at 30 A g-1. A further increase in the cyclability (~107%) was achieved by employing a graphene hybrid. Further, an asymmetric supercapacitor device was fabricated, that delivers reasonably high energy density of 12.7 Wh kg-1 at a power density of 370 W kg-1 and cycling stability of ~93% after 10000 cycles. This study reports on the modulation of interfacial properties of CoPx/CoO heterostructure to enhance energy storage performance via bulk/surface compositional variation, thereby providing a strategy to develop heterostructure electrodes for high-performance supercapacitor.
RESUMEN
Zeolitic imidazolate framework (ZIF)-derived materials have been explored as promising electrode for energy storage, owing to their tunable composition, high porous structure, and heteroatom-based active sites. Herein, we report cobalt phosphide-draped N-doped carbon/graphene hybrid (CoP-NPC/GS) synthesized from ZIF-67 precursor via a single-step in-situ carbonization and phosphidation. The CoP-NPC/GS hybrid performed as a promising positive electrode with superior electrochemical performance - high capacitance (165 F g-1 at 7 A g-1 compared to 97 F g-1 for CoP-NPC), enhanced rate capability, and promoted cycling stability (~88% after 10,000 cycles). Excellent performance of the CoP-NPC/GS was derived from scanty graphene (2 wt%)-driven compositional variation, which promotes the redox-active CoP phase and higher nitrogen content offering enhanced electronic conductivity. Besides, CoP-NPC/GS performed well as a negative electrode, derived from double-layer capacitance of porous carbon, realizing a capacitance of ~71 F g-1 at 1 A g-1 but inferior to CoP-NPC, which was regulated by pyridinic nitrogen-induced pseudocapacitance. A fabricated CoP-NPC/GS||CoP-NPC asymmetric device displayed an energy density of 10 Wh Kg-1 at 700 W kg-1, with excellent cyclability (~100%) till 11,000 cycles. This study clarifies the role of scanty graphene on the phase control and heteroatom functionalization of phosphide-based electrode, beneficial for enhanced supercapacitive performance.