Coupling of Bifunctional CoMn‐Layered Double Hydroxide@Graphitic C₃N₄ Nanohybrids towards Efficient Photoelectrochemical Overall Water Splitting

Abstract

The development of durable, low-cost, and efficient photo-/electrolysis for the oxygen and hydrogen evolution reactions (OER and HER) is important to fulfill increasing energy requirements. Herein, highly efficient and active photo-/electrochemical catalysts, that is, CoMn-LDH@g-C N hybrids, have been synthesized successfully through a facile in situ co-precipitation method at room temperature. The CoMn-LDH@g-C N composite exhibits an obvious OER electrocatalytic performance with a current density of 40 mA cm at an overpotential of 350 mV for water oxidation, which is 2.5 times higher than pure CoMn-LDH nanosheets. For HER, CoMn-LDH@g-C N (η =-448 mV) requires a potential close to Pt/C (η =-416 mV) to reach a current density of 50 mA cm . Furthermore, under visible-light irradiation, the photocurrent density of the CoMn-LDH@g-C N composite is 0.227 mA cm , which is 2.1 and 3.8 time higher than pristine CoMn-LDH (0.108 mA cm ) and g-C N (0.061 mA cm ), respectively. The CoMn-LDH@g-C N composite delivers a current density of 10 mA cm at 1.56 V and 100 mA cm at 1.82 V for the overall water-splitting reaction. Therefore, this work establishes the first example of pure CoMn-LDH and CoMn-LDH@g-C N hybrids as electrochemical and photoelectrochemical water-splitting systems for both OER and HER, which may open a pathway to develop and explore other LDH and g-C N nanosheets as efficient catalysts for renewable energy applications.

One‐Step Synthesis of NiFe Layered Double Hydroxide Nanosheet Array/N‐Doped Graphite Foam Electrodes for Oxygen Evolution Reactions

“…To improve the intrinsic conductivity, LDH coupled with carbonaceous materials (graphene, carbon nanotubes, and carbon quantum dots etc.) has been widely explored . Moreover, the introduction of nitrogen dopants in these nanocarbons has been demonstrated as an efficient mean to further improve the dispersion of LDHs and the charge transfer because of the created anchoring sites and enhanced electron‐donor property, respectively …”

“…has been widely explored. [28][29][30][31] Moreover, the introduction of nitro-gen dopants in these nanocarbons has been demonstrated as an efficient mean to further improve the dispersion of LDHs and the charge transfer because of the created anchoring sites and enhanced electron-donor property, respectively. [32][33][34][35] The mass transport and diffusion issue during OER should also be considered since it occurs at the triple-phase boundary regions.…”

Recent Advances in Composites of Graphene and Layered Double Hydroxides for Water Remediation: A Review

“…[1][2][3] LDH materials can be expresseda ccording to the general formula [M 2+ + 1Àp M 3+ + p (OH) 2 ] p+ + [(A qÀ ) p/q ] pÀ ·y H 2 O, in which M 2+ + and M 3+ + represent bi-/trivalent metal cations (e.g.,M g 2+ + ,C a 2+ + ,N i 2+ + ,A l 3+ + , and Fe 3+ + ), A qÀ represents nonframework (in)organic q-valent interlayera nions( e.g.,N O 3 À ,C lO 4 À ,a nd SO 4 2À ), p denotes the molar ratio of M 2+ + /(M 2+ + + +M 3+ + ), and y denotes the molar amount of intercalated water. [4][5][6][7] Different elemental compositions and metal ratios can greatlyi nfluence the morphology and crystal form of these composite materials, which directly impact the basal spacing and interlayer region in the LDH, as well as indirectly impactingt heir applications. Owing to their particular structuralm erits,s uch as large interlayer spacing, broad chemical composition, and ion-exchange ability,L DH materials have been extensively investigated as catalysts or ad-sorbents in the field of water remediation.…”

Crossed NiCo2S4 Nanowires Supported on Nickel Foam as a Bifunctional Catalyst for Efficient Overall Water Splitting

“…Electrochemical water splitting, which consists of two half reactions oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is regarded as a new environment‐friendly method for hydrogen production . In order to expedite reaction rate and decrease overpotential, an efficient, cost effective and robust overall water splitting electrocatalyst is critically required . For the moment, Ir‐ and Ru‐based precious‐metal compounds have been distinguished to be the most prosperous OER and HER catalysts, but high cost and limited resources prohibit their widespread applications .…”