RESUMO
A new family of single-atom-thick 2D germanium-based materials with graphene-like atomic arrangement, germanene and functionalized germanene, has attracted intensive attention due to their large bandgap and easily tailored electronic properties. Unlike carbon atoms in graphene, germanium atoms tend to adopt mixed sp2 /sp3 hybridization in germanene, which makes it chemically active on the surface and allows its electronic states to be easily tuned by chemical functionalization. Impressive achievements in terms of the applications in energy storage and catalysis have been reported by using germanene and functionalized germanene. Herein, the fabrication of epitaxial germanene on different metallic substrates and its unique electronic properties are summarized. Then, the preparation strategies and the fundamental properties of hydrogen-functionalized germanene (germanane or GeH) and other ligand-terminated forms of germanene are presented. Finally, the progress of their applications in energy storage and catalysis, including both experimental results and theoretical predictions, is analyzed.
RESUMO
In this work, 2D ferromagnetic M3GeTe2 (MGT, M = Ni/Fe) nanosheets with rich atomic Te vacancies (2D-MGTv) are demonstrated as efficient OER electrocatalyst via a general mechanical exfoliation strategy. X-ray absorption spectra (XAS) and scanning transmission electron microscope (STEM) results validate the dominant presence of metal-O moieties and rich Te vacancies, respectively. The formed Te vacancies are active for the adsorption of OH* and O* species while the metal-O moieties promote the O* and OOH* adsorption, contributing synergistically to the faster oxygen evolution kinetics. Consequently, 2D-Ni3GeTe2v exhibits superior OER activity with only 370 mV overpotential to reach the current density of 100 mA cm-2 and turnover frequency (TOF) value of 101.6 s-1 at the overpotential of 200 mV in alkaline media. Furthermore, a 2D-Ni3GeTe2v-based anion-exchange membrane (AEM) water electrolysis cell (1 cm2) delivers a current density of 1.02 and 1.32 A cm-2 at the voltage of 3 V feeding with 0.1 and 1 m KOH solution, respectively. The demonstrated metal-O coordination with abundant atomic vacancies for ferromagnetic M3GeTe2 and the easily extended preparation strategy would enlighten the rational design and fabrication of other ferromagnetic materials for wider electrocatalytic applications.
RESUMO
Functional and robust catalyst supports are vital in the catalysis field, and the development of universal and efficient catalyst support is essential but challenging. Traditional catalyst fabrication methods include the carbonization of ordered templates and high-temperature dehydration. All these methods involve complicated meso-structural disordering and allow little control over morphology. To this end, a eutectic GaInSn alloy (EGaInSn) was proposed and employed as an intermediate to fabricate low-dimensional ordered catalyst support materials. Owing to the lower Gibbs free energy of Ga2O3 compared to certain types of metals (e.g., Al, Mn, Ce, etc.), we found that a skinny layer of metal oxides could be formed and exfoliated into a two-dimensional nanosheet at the interface of liquid metal (LM) and water. As such, EGaInSn was herein employed as a reaction matrix to synthesize a range of two-dimensional catalyst supports with large specific surface areas and structural stability. As a proof-of-concept, Al2O3 and MnO were fabricated with the assistance of LM and were used as catalyst supports for loading Ru, demonstrating enhanced structural stability and overall electrocatalytic performance in the oxygen evolution reaction. This work opens an avenue for the development of functional support materials mediated by LM, which would play a substantial role in electrocatalytic reactions and beyond.