Porous β-MnO2 nanoplates derived from MnCO3 nanoplates as highly efficient electrocatalysts toward oxygen evolution reaction

β-MnO2 has not been considered as an effective catalyst toward the oxygen evolution reaction due to its lack of active di-μ2-oxo bridged Mn centres and inaccessibility to the inner Mn atoms. We have envisioned that β-MnO2 can be made catalytically active by making the inner Mn atoms accessible. In order to accomplish this, we have synthesized MnCO3 nanoplates via a solution route and converted them into highly porous β-MnO2 nanoplates with very high surface area. In addition to the reduced overpotential of 450 mV at 10 mA cm-2, the derived Tafel slope was 78.2 mV dec-1, showing a superior catalytic activity of the porous nanoplate, which is comparable to the catalytic performance of best performing α-MnO2 phase. The importance of surface-bound catalytic Mn sites in highly porous β-MnO2 nanoplates is also demonstrated by Au loading-induced blockage of them and corresponding catalytic activity deterioration. © 2016 The Royal Society of Chemistry1891sciescopu

Flattening bent Janus nanodiscs expands lattice parameters

Nanoscale lattice parameter engineering is a potentially powerful tool for tailoring the electronic properties of nanomaterials. The nascent strain in juxtaposed hetero-interfaces of nanocrystals was recently shown to substantially affect the energy states of the exposed surfaces and improve catalytic activity; however, practical implementations of this design strategy are rare. Herein, we report that Rh3S4 and Cu31S16 can be combined to produce a bent Janus-type nanodisc in which the surface strain can be controlled precisely by modulating the curvature. These nanodiscs are conveniently prepared by replacing copper with rhodium in Cu31S16 via anisotropic cation exchange, which induces lattice strain and bends the nanodiscs. Flattening the Rh3S4/Cu31S16 nanodisc leads to a unique surface lattice structure and affords superior electrocatalytic performance in the hydrogen evolution reaction. We demonstrate a general and straightforward strategy for controlling the lattice strains in hetero-nanostructures and for systematically improving their catalytic performance.ª2022ElsevierInc.11Nsciescopu

RhCu 3D Nanoframe as a Highly Active Electrocatalyst for Oxygen Evolution Reaction under Alkaline Condition

One pot synthesis of RhCu alloy truncated octahedral nanoframes, Cu@Rh core–shell nanoparticles, and a bundle of five RhCu nanowires is demonstrated. The RhCu alloy 3D nanoframe, in particular, exhibits excellent catalytic activity toward the oxygen evolution reaction under alkaline conditions. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim113131sciescopu

Porous beta-MnO2 nanoplates derived from MnCO3 nanoplates as highly efficient electrocatalysts toward oxygen evolution reaction

beta-MnO2 has not been considered as an effective catalyst toward the oxygen evolution reaction due to its lack of active di-mu(2)-oxo bridged Mn centres and inaccessibility to the inner Mn atoms. We have envisioned that beta-MnO2 can be made catalytically active by making the inner Mn atoms accessible. In order to accomplish this, we have synthesized MnCO3 nanoplates via a solution route and converted them into highly porous beta-MnO2 nanoplates with very high surface area. In addition to the reduced overpotential of 450 mV at 10 mA cm(-2), the derived Tafel slope was 78.2 mV dec(-1), showing a superior catalytic activity of the porous nanoplate, which is comparable to the catalytic performance of best performing alpha-MnO2 phase. The importance of surface-bound catalytic Mn sites in highly porous beta-MnO2 nanoplates is also demonstrated by Au loading-induced blockage of them and corresponding catalytic activity deterioration.

Synthesis of compositionally tunable, hollow mixed metal sulphide CoxNiySz octahedral nanocages and their composition-dependent electrocatalytic activities for oxygen evolution reaction

Hollow nanostructures such as nanocages and nanoframes can serve as advanced catalysts with their enlarged active surface areas, and hence they have been of widespread interest. Despite the recent progress in the synthesis of this class of nanomaterials, hollow nanostructures with tunable compositions and controlled morphologies have rarely been reported. Here, we report a facile synthetic route to a series of compositionally tunable, hollow mixed metal sulphide (CoxNiySz) octahedral nanocages. The sulfidation of CoO octahedral nanoparticles generates CoO@CoxSy core-shell octahedra, and the in situ etching of the CoO core and annealing yield Co9S8 (pentlandite) octahedral nanocages (ONC). The addition of a Ni precursor during the etching/annealing process of CoO@CoxSy core-shell octahedra progressively yields hollow ONC structures of Co9-xNixS8, Ni9S8, Ni9S8/??-NiS, and Ni3S2/??-NiS via cation exchange reactions. Mixed cobalt/nickel sulphide, Co9-xNixS8 ONC, shows superior oxygen evolution reaction activity to monometallic sulphide ONC structures, demonstrating the synergy between different metal species

Iridium-Based Multimetallic Nanoframe@Nanoframe Structure: An Efficient and Robust Electrocatalyst toward Oxygen Evolution Reaction

Nanoframe electrocatalysts have attracted great interest due to their inherently high active surface area per a given mass. Although recent progress has enabled the preparation of single nanoframe structures with a variety of morphologies, more complex nanoframe structures such as a double-layered nanoframe have not yet been realized. Herein, we report a rational synthetic strategy for a structurally robust Ir-based multimetallic double-layered nanoframe (DNF) structure, nanoframe@nanoframe. By leveraging the differing kinetics of dual Ir precursors and dual transition metal (Ni and Cu) precursors, a core shell-type alloy@alloy structure could be generated in a simple one-step synthesis, which was subsequently transformed into a multimetallic IrNiCu DNF with a rhombic dodecahedral morphology via selective etching. The use of single Ir precursor yielded single nanoframe structures, highlighting the importance of employing dual Ir precursors. In addition, the structure of Ir-based nanocrystals could be further controlled to DNF with octahedral morphology and CuNi@Ir core shell structures via a simple tuning of experimental factors. The IrNiCu DNF exhibited high electrocatalytic activity for oxygen evolution reaction (OER) in acidic media, which is better than Ir/C catalyst. Furthermore, IrNiCu DNF demonstrated excellent durability for OER, which could be attributed to the frame structure that prevents the growth and agglomeration of particles as well as in situ formation of robust rutile II, phase during prolonged operation

Plasmon Enhanced Direct Bandgap Emissions in Cu7S4@Au2S@Au Nanorings

Nanostructured copper sulfides, promising earth-abundant p-type semiconductors, have found applications in a wide range of fields due to their versatility, tunable low bandgap, and environmental sustainability. The synthesis of hexagonal Cu7S4@Au2S@Au nanorings exhibiting plasmon enhanced emissions at the direct bandgap is reported. The synthesized Cu7S4@Au2S@Au nanorings show greatly enhanced absorption and emission by local plasmons compared to pure copper sulfide nanoparticles. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim1321sciescopu

Facet-controlled Rh3Pb2S2 nanocage as an efficient and robust electrocatalyst toward hydrogen evolution reaction

Highly active and durable electrocatalysts for the hydrogen evolution reaction (HER) may play a pivotal role in commercial success of electrolytic water splitting technology. Among various material classes, binary metal sulphides show a great promise as HER catalysts because of their tunable energy levels conducive to a high catalytic activity and high robustness under harsh operating conditions. On the other hand, facet-controlled nanoparticles with controlled surface energies have gained great recent popularity as active and selective catalysts. However, binary metal sulphide nanoparticles with well-defined facets and high surface areas are very rare. Herein we report the synthesis of a facet-controlled hollow Rh3Pb2S2 nanocage as a new catalytic material and its excellent activity (overpotential: 87.3 mV at 10 mA cm−2) and robustness toward HER under harsh acidic conditions. © The Royal Society of Chemistry 201