Space-Confined Earth-Abundant Bifunctional Electrocatalyst for High-Efficiency Water Splitting

Abstract

Hydrogen generation from water splitting could be an alternative way to meet increasing energy demands while also balancing the impact of energy being supplied by fossil-based fuels. The efficacy of water splitting strongly depends on the performance of electrocatalysts. Herein, we report a unique space-confined earth-abundant electrocatalyst having the bifunctionality of simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), leading to high-efficiency water splitting. Outperforming Pt/C or RuO catalysts, this mesoscopic, space-confined, bifunctional configuration is constructed from a monolithic zeolitic imidazolate framework@layered double hydroxide (ZIF@LDH) precursor on Ni foam. Such a confinement leads to a high dispersion of ultrafine CoO nanoparticles within the N-doped carbon matrix by temperature-dependent calcination of the ZIF@LDH. We demonstrate that the OER has an overpotential of 318 mV at a current density of 10 mA cm, while that of HER is -106 mV @ -10 mA cm. The voltage applied to a two-electrode cell for overall water splitting is 1.59 V to achieve a stable current density of 10 mA cm while using the monolithic catalyst as both the anode and the cathode. It is anticipated that our space-confined method, which focuses on earth-abundant elements with structural integrity, may provide a novel and economically sound strategy for practical energy conversion applications.

Host-Guest Engineering of Layered Double Hydroxides towards Efficient Oxygen Evolution Reaction: Recent Advances and Perspectives

“…In addition to direct co-precipitation, the template-directed method is another effective strategy for the synthesis of LDH arrays as efficient OER electrocatalysts [122][123][124]. Sun et al develop a two-step hydrothermal method to synthesize hierarchical NiCoFe-LDH NSAs [125].…”

Self‐Supported Electrocatalysts for Efficient Oxygen Evolution Reaction: Hierarchical CuOx@CoO Nanorods Grown on Cu Foam

“…However, the appearing of Co 3+ was attributed to the oxidation of Co 2+ valence due to the reduction of CuO, which illustrated the existed effect between Cu and Co. The O 1s spectra of CuO x @CoO NRs/CF was fitted into two peaks which originated from the metal‐oxygen binding (noted as M−O) at 529.53 eV and adsorbed‐OH (noted as ‐OH) at 530.88 eV, suggesting an appearance of metallic oxides during thermal annealing progress . Furthermore, the C 1s spectrum showed three peaks at 284.75, 286.10, and 288.47 eV (Figure S8), assigned to the contributions of C=C, C−O and C−N, respectively .…”

“…The O 1s spectra of CuO x @CoO NRs/CF was fitted into two peaks which originated from the metal-oxygen binding (noted as MÀ O) at 529.53 eV and adsorbed-OH (noted as -OH) at 530.88 eV, suggesting an appearance of metallic oxides during thermal annealing progress. [26] Furthermore, the C 1s spectrum showed three peaks at 284.75, 286.10, and 288.47 eV ( Figure S8), assigned to the contributions of C=C, CÀ O and CÀ N, respectively. [24] The N 1s spectrum was divided into two peaks that the contribution of 398.70 eV was attributed to the pyridinic nitrogen species and the designation of 400.29 eV was the graphite nitrogen species.…”

Boosting Electrocatalytic Hydrogen Evolution of Nickel foam Supported Nickel Hydroxide by Ruthenium Doping

“…In many cases, nickel foam (NF) was used as electrode substrate for the growth various 2D nanosheets, which showed higher HER activity, due to large porosity and good conductivity of NF. [37][38][39][40][41][42][43] According to the above discussion, herein, we report the synthesis of ruthenium doped nickel hydroxide on nickel foam (RuÀ Ni(OH) 2 /NF) with nickel chloride hexahydrate and ruthenium chloride hydrate as nickel and ruthenium sources by using the facile and environmentally friendly hydrothermal method (Scheme 1). The as-synthesized RuÀ Ni(OH) 2 /NF was explored as the electrochemical catalyst for HER in acidic media.…”