Bifunctional 2D Superlattice Electrocatalysts of Layered Double Hydroxide–Transition Metal Dichalcogenide Active for Overall Water Splitting

Abstract

Bifunctional 2D superlattice electrocatalysts of alternating layered double hydroxide (LDH)−transition metal dichalcogenide (TMD) heterolayers were synthesized by interstratification of the exfoliated nanosheets. Density functional theory calculations predict an increased interfacial charge transfer between interstratified LDH and TMD nanosheets, which would lead to enhanced electrocatalytic activity. The electrostatically driven self-assembly of oppositely charged 2D building blocks, i.e., exfoliated Ni−Al-LDH/Ni−Fe-LDH and MoS 2 nanosheets, yields mesoporous heterolayered Ni−Al-LDH−MoS 2 /Ni−Fe-LDH−MoS 2 superlattices. The synthesized superlattices show improved electrocatalytic activity with enhanced durability for oxygen and hydrogen evolution reactions and water splitting. The interstratification improves the chemical stability of LDH in acidic media, thus expanding its possible applications. The high electrocatalytic activity of the superlattices may be attributed to an enhanced affinity for OH − /H + , improved electrical conduction and charge transfer, and the increase of active sites. This study indicates that the formation of superlattices via self-assembly of 2D nanosheets provides useful methodology to explore high-performance electrocatalysts with improved stability.

Alternate Restacking of 2 D CoNi Hydroxide and Graphene Oxide Nanosheets for Energetic Oxygen Evolution

“…Figure 6d and Ta ble S4 list the OER activities of Co 2/3 Ni 1/3 NS-GO superlattice andr ecently reportede lectrocatalysts. For electrocatalytic water oxidation, owing to the united merits of superlattice heterostructure and composition tuning, Co 2/3 Ni 1/3 -NS-GO superlattice in this work outperformed congeneric transition metal hydroxide-based electrocatalysts, such as CoNi hydroxide nanoplates, [23] Fe-doped Co(OH) 2 nanosheets, [24] NiFeCr LDH, [25] and restacking NiAl LDH/MoS 2 and NiFe LDH/MoS 2 superlattices, [26] as well as other outstanding electrocatalysts, such as NiFe@N-doped graphene (NiFe@NC), [27] black phosphorus (BP), [28] hollow NiCo 2 O 4 microcuboids, [21] and FeNi 3 /Fe 3 O 4 . [29]…”

2D Superlattices for Efficient Energy Storage and Conversion

“…A single AA battery of 1.5 V was able to power an electrolyzer cell using the superlattices as bifunctional catalysts (Figure i). Recently, a MoS 2 /LDH superlattice has been explored by heteroassembly of oppositely charged LDH and MoS 2 nanosheets . The chemical stability of LDH in acidic media was improved due to the inter‐stratification structure .…”

“…Recently, a MoS 2 /LDH superlattice has been explored by heteroassembly of oppositely charged LDH and MoS 2 nanosheets . The chemical stability of LDH in acidic media was improved due to the inter‐stratification structure . Compared with the bulk layered materials, the loosely restacked superlatttices with limited number of stacked nanosheets may offer more accessible active sites for enhanced performances .…”

Defect‐Rich Heterogeneous MoS2/NiS2 Nanosheets Electrocatalysts for Efficient Overall Water Splitting

“…[1,7] Considering that surfaces or interfaces play the key role in electrochemical reactions, the morphology, surface defects or interfaces, and electrical structures are the key factors on the electrocatalytic performances of efficient catalysts. [16,17] In particular, in situ growing nanosheet nanostructures on conductive substrates, such as Ni foam, carbon cloth, and stainless steel, could supply the efficient pathways for charge transport and provide open channels for rapid release of gas bubbles during OER or HER process. [16,17] In particular, in situ growing nanosheet nanostructures on conductive substrates, such as Ni foam, carbon cloth, and stainless steel, could supply the efficient pathways for charge transport and provide open channels for rapid release of gas bubbles during OER or HER process.…”