to the efficiency loss of the overall electrochemical process. [2] Therefore, efficient OER electrocatalyst is a cornerstone for the sustainable energy storage and conversion technologies. [3] Noble-metal-based catalysts such as Ru and Ir oxides have been reported to be excellent OER catalysts; [4] however, their low natural abundance and higher cost render their widespread commercial utilization impractical.[5] Thus, developing efficient, durable, and cost-effective catalytic materials for OER is crucial, but so far still remains a great challenge.Recently, various metal-metalloid compound materials such as chalcogenides, nitrides, and phosphides have been reported to exhibit promising OER electrocatalytic activities. [6] This has been attributed to the charge transfer between different elements and the modified electronic structures, and consequently lowers the kinetic energy barriers of the electrochemical processes. [7] In this regard, to extend such applications on metal borides is reasonable, wherein metal borides share certain properties with other metal-metalloids, such as bonding schema in metal phosphides. [8] Recently, the application of monometallic borides such as cobalt boride, iron boride, and nickel boride as well as cobalt-borate-based graphene hybrid as oxygen-evolving catalyst has been reported to exhibit promising electrocatalytic activity for OER in alkaline media. [9] However, multimetal-metalloid boron-based material, herein referred to as an amorphous quaternary metal boride, for simplicity, as oxygen-evolving electrocatalyst, reported to date is very limited. Thus, it is still of great interest to develop metal-boride-based OER catalysts and further to explore their catalytic activities. The as-identified approach to enhance electrochemical OER properties in metalmetalloid material opens a new avenue in related applications for energy devices that involve OER such as water electrolysis and metal-air batteries.Despite the complicated structure of amorphous material, well-characterized amorphous nanomaterial as oxygen-evolving material has received attention due to the unique properties such as higher catalytic selectivity and activity. [10] A great number of under-coordinated metal atoms, and hence abundant defects, in amorphous nanomaterial may provide more reactive sites at the catalyst surface, and as a result, facilitating the binding of hydroxyls and thus enhancing OER performance. [11] Furthermore, these amorphous nanomaterials have attracted much attention in other electrochemical applications Cost-effective and efficient oxygen-evolving electrocatalysts are urgently required for energy storage and conversion technologies. In this work, an amorphous trimetallic boride nanocatalyst (Fe-Co-2.3Ni-B) prepared by a simple approach is reported as a highly efficient oxygen evolution reaction electrocatalyst. It exhibits an overpotential (η) of 274 mV to deliver a geometric current density (j geo ) of 10 mA cm −2 , a small Tafel slope of 38 mV dec −1 , and excellent long-term durabil...

The low-cost hydrogen production from water electrolysis is crucial for deployment of sustainable hydrogen economy, but is currently constrained by the lack of active and robust electrocatalysts from Earth-abundant materials. We describe here an unconventional heterostructure composed of strongly coupled Ni-deficient LixNiO nanoclusters and polycrystalline Ni nanocrystals, and its exceptional activities toward hydrogen evolution reaction (HER) in aqueous electrolytes. The presence of lattice oxygen species with strong Brønsted basicity is a significant feature in such heterostructure, which spontaneously split water molecules for accelerated Volmer H-OH dissociation in neutral and alkaline HER. In combination with the intimate LixNiO and Ni interfacial junctions that generate localized hotspots for promoted hydride coupling and hydrogen desorption, the catalysts produce hydrogen at the current density of 10 mA cm -2 under overpotentials of only 20, 50 and 36 mV in acidic, neutral and alkaline electrolytes, respectively, making them among the most active Pt-free catalyst developed thus far. In addition, such heterostructure also exhibited superior activity towards the hydrogen oxidation reaction in alkaline electrolyte.

Donor-acceptor (D-A) type semiconducting polymers have shown great potential for the application of deformable and stretchable electronics in recent decades. However, due to their heterogeneous structure with rigid backbones and long solubilizing side chains, the fundamental understanding of their molecular picture upon mechanical deformation still lacks investigation. Here, the molecular orientation of diketopyrrolopyrrole (DPP)-based D-A polymer thin films is probed under tensile deformation via both experimental measurements and molecular modeling. The detailed morphological analysis demonstrates highly aligned polymer crystallites upon deformation, while the degree of backbone alignment is limited within the crystalline domain. Besides, the aromatic ring on polymer backbones rotates parallel to the strain direction despite the relatively low overall chain anisotropy. The effect of side-chain length on the DPP chain alignment is observed to be less noticeable. These observations are distinct from traditional linear-chain semicrystalline polymers like polyethylene due to distinct characteristics of backbone/side-chain combination and the crystallographic characteristics in DPP polymers. Furthermore, a stable and isotropic charge carrier mobility is obtained from fabricated organic field-effect transistors. This study deconvolutes the alignment of different components within the thin-film microstructure and highlights that crystallite rotation and chain slippage are the primary deformation mechanisms for semiconducting polymers.

Nano-structured microemulsion reversibly responds to CO2 and N2, accompanied with an alternate transition from monophasic microemulsion to near-complete phase separation.