A Complementary Co−Ni Phosphide/Bimetallic Alloy‐Interspersed N‐Doped Graphene Electrocatalyst for Overall Alkaline Water Splitting

Abstract

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 300 mV in 1 M KOH at 10 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=150 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 1.76 V at 10 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.

Co/MoC Nanoparticles Embedded in Carbon Nanoboxes as Robust Trifunctional Electrocatalysts for a Zn–Air Battery and Water Electrocatalysis

“…In order to understand the ORR reaction kinetics in depth, the corresponding Tafel slopes are plotted and displayed in Figure c. In general, a lower Tafel slope at a low overpotential region implies efficient kinetics in the catalytic process. ,− Interestingly, the Co@IC/MoC@PC sample also possesses the smallest Tafel slope of 78 mV/dec, thus suggesting its excellent kinetics. The charge-transfer resistance could be measured by the electrochemical impedance spectroscopy (EIS).…”

“…With the increasingly serious energy gaps and environmental pollution, rechargeable metal–air battery and electrocatalytic overall water splitting (EOWS) have gradually attracted strong research interest due to their expected advantages such as high capacity, sustainability, and environmental friendliness and are therefore hailed as ideal and efficient energy conversion and storage technologies. − The core processes of these two catalytic systems mainly depend on three half-reactions, i.e ., hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). − However, these reactions usually involve multiple-electron transfer processes, thus leading to slow kinetics and high overpotentials. − Although the uses of precious metal-based materials can improve these reaction efficiencies ( i.e ., Pt/C only for the ORR and HER, IrO 2 and RuO 2 only for the OER), their earth scarcity, high cost, and insufficient catalytic functions (single/dual catalytic functions) inevitably hinder the widespread technological applications. − Thus, the development of trifunctional electrocatalysts based on the earth-abundant nonprecious metals that can synchronously enhance the electrocatalytic efficiencies toward OER, HER, and OER is extremely paramount yet challenging. − …”

The Scalable Solid-State Synthesis of a Ni5P4/Ni2P–FeNi Alloy Encapsulated into a Hierarchical Porous Carbon Framework for Efficient Oxygen Evolution Reactions

“…After the long-term OER test, the peaks of the M–P bond disappear, and the single peak at 133.8 eV corresponds to P–O. This phenomenon may be caused by massive P leaching and the rearrangement and oxidation of metal phosphide (Ni 5 P 4 -Ni 2 P) after the OER reaction [ 37 ]. For the spectrum of O 1s in Figure 7 b, the initial peaks at 531.8 and 533.5 eV are assigned to O–H and C–O/C = O, respectively [ 38 ].…”

Engineering Metal Alloy Nanocrystals Anchored on N‐Doped Nanoporous Carbon for Li‐O2 Batteries

“…[31][32][33] For instance, Zhu et al [34] synthesized FeNi alloys embedded in N-doped carbon matrix as an oxygen electrocatalyst for zinc-air battery using MOF precursor, which exhibits high ORR/OER catalytic activity. Guo et al [35] prepared an excellent ORR electrocatalyst by embedding NiCo alloys into N-doped carbon nanowires and demonstrated that it could maintain high ORR activity in alkaline solutions for more than 50 h. Arunkumar et al [36] reported CoNiP/CoNi alloys anchored on N-doped graphene as efficient electrocatalysts for OER, which was mainly attributed to the synergistic effect of Co and Ni metals. Although some progress has been achieved in recent years, it is still challenging to explore the engineered methods to produce these carbon-based materials used for LOBs.…”