Metal–Organic Framework–Derived Mesoporous B‐Doped CoO/Co@N‐Doped Carbon Hybrid 3D Heterostructured Interfaces with Modulated Cobalt Oxidation States for Alkaline Water Splitting

Abstract

Heteroatom‐doped transition metal‐oxides of high oxygen evolution reaction (OER) activities interfaced with metals of low hydrogen adsorption energy barrier for efficient hydrogen evolution reaction (HER) when uniformly embedded in a conductive nitrogen‐doped carbon (NC) matrix, can mitigate the low‐conductivity and high‐agglomeration of metal‐nanoparticles in carbon matrix and enhances their bifunctional activities. Thus, a 3D mesoporous heterostructure of boron (B)‐doped cobalt‐oxide/cobalt‐metal nanohybrids embedded in NC and grown on a Ni foam substrate (B‐CoO/Co@NC/NF) is developed as a binder‐free bifunctional electrocatalyst for alkaline water‐splitting via a post‐synthetic modification of the metal–organic framework and subsequent annealing in different Ar/H2 gas ratios. B‐CoO/Co@NC/NF prepared using 10% H2 gas (B‐CoO/Co@NC/NF [10% H2]) shows the lowest HER overpotential (196 mV) and B‐CoO/Co@NC/NF (Ar), developed in Ar, shows an OER overpotential of 307 mV at 10 mA cm−2 with excellent long‐term durability for 100 h. The best anode and cathode electrocatalyst‐based electrolyzer (B‐CoO/Co@NC/NF (Ar)(+)//B‐CoO/Co@NC/NF (10% H2)(−)) generates a current density of 10 mA cm−2 with only 1.62 V with long‐term stability. Further, density functional theory investigations demonstrate the effect of B‐doping on electronic structure and reaction mechanism of the electrocatalysts for optimal interaction with reaction intermediates for efficient alkaline water‐splitting which corroborates the experimental results.

Confinement engineering for enhanced electrocatalytic nitrate reduction by integrating B-doped graphene with iron catalysts for long-term stability

“…2d). 45 The high-resolution B 1s peak of Fe@B-Gnc could be fitted to four peaks, which corresponded to the structures of B–O (193.6 eV), BCO 2 (192.3 eV), BC 2 O (191.2 eV), and BC 3 (189.9 eV) (Fig. 2e).…”

A Bifunctional Electrocatalyst of Flower-Like Cr-Doped CoP/Fe2P Microsphere for Efficient Overall Water Splitting

“…The OER activity of Cr-CoP/Fe 2 P has exceeded that of many previously reported Co-based electrocatalysts. 21,36,[68][69][70] Although the overpotential of Cr-CoP/Fe 2 P is larger than that of RuO 2 (231 mV) at 10 mA cm −2 , the Cr-CoP/Fe 2 P can generate a higher current density than RuO 2 when exceeding a certain overpotential (>299 mV). For instance, Cr-CoP/Fe 2 P only requires an overpotential of 417 mV to obtain the current density of 500 mA cm −2 meanwhile the RuO 2 needs 600 mV (Fig.…”

“…5b) and the current density remained stable with no significant decline, indicating outstanding stability that favors practical applications. 53,70,[78][79][80] Moreover, the Faradaic efficiency of the Cr-CoP/Fe 2 P was estimated by means of the water drainage method (Figs. 5c and S16).…”

A critical review on amorphous–crystalline heterostructured electrocatalysts for efficient water splitting

“…In two of our most recent works, experimental findings combined with ab initio investigations have successfully illustrated the reaction mechanism of alkaline water splitting using amorphous-crystalline heterostructure electrocatalysts. 3,49 DFT is increasingly being used as a tool to design novel electrocatalysts using a rational approach.…”

“…Green technologies for energy conversion and storage systems, such as water splitting, rechargeable batteries, and fuel cells, are highly sought after to mitigate the problems associated with renewable energy sources or traditional energy scenarios. [3][4][5] Hydrogen fuel is considered a zero-emission alternative energy carrier because of its wide range of sources and high combustion calorific value. It can provide clean, non-toxic energy with zero pollution and could be a promising energy carrier owing to its multiple advantages, such as its high utilization rate, ready usability, and contribution to the reduction of the greenhouse effect.…”