RESUMO
The rational design of pH-universal electrocatalyst with high-efficiency, low-cost and large current output suitable for industrial hydrogen evolution reaction (HER) is crucial for hydrogen production via water splitting. Herein, phase engineering of ruthenium (Ru) electrocatalyst comprised of metastable unconventional face-centered cubic (fcc) and conventional hexagonal close-packed (hcp) crystalline phase supported on nitrogen-doped carbon matrix (fcc/hcp-Ru/NC) is successfully synthesized through a facile pyrolysis approach. Fascinatingly, the fcc/hcp-Ru/NC displayed excellent electrocatalytic HER performance under a universal pH range. To deliver a current density of 10 mA cm-2, the fcc/hcp-Ru/NC required overpotentials of 16.8, 23.8 and 22.3 mV in 1 M KOH, 0.5 M H2SO4 and 1 M phosphate buffered solution (PBS), respectively. Even to drive an industrial-level current density of 500 and 1000 mA cm-2, the corresponding overpotentials are 189.8 and 284 mV in alkaline, 202 and 287 mV in acidic media, respectively. Experimental and theoretical calculation result unveiled that the charge migration from fcc-Ru to hcp-Ru induced by work function discrepancy within fcc/hcp-Ru/NC regulate the d-band center of Ru sites, which facilitated the water adsorption and dissociation, thus boosting the electrocatalytic HER performance. The present work paves the way for construction of novel and efficient electrocatalysts for energy conversion and storage.
RESUMO
The exploitation of an extraordinary and low-cost electrocatalyst to solve energy shortage and environmental pollution issues is crucial. Herein, a topological Archimedean polyhedron of CoFe PBA (Prussian blue analogue) was synthesized via a Sn-induced crystal growth regulation strategy. After phosphating treatment of the as-prepared Sn-CoFe PBA, a Sn-doped binary CoP/FeP hybrid was obtained (Sn-CoP/FeP). Benefiting from the rough polyhedral surface and internal porous structure of Sn-CoP/FeP, when served as a highly efficient electrocatalyst, it exhibited outstanding HER performance, i.e., to drive a current density of 10 mA cm-2, it required a low overpotential of 62 mV in alkaline medium, along with a long-term cycling stability for 35 h. This work is of great significance for the development of indispensable novel catalysts for hydrogen production, and would shed new light on the topology-related performance of electrocatalysts for energy storage and conversion.
RESUMO
The electrochemical and paramagnetic properties of endohedral metallofullerenes (EMFs) have drawn extensive attention due to their huge potential in the fields of molecular devices, biomedicines, quantum information processing, etc. Exohedral modification of the fullerene carbon cage, such as in the classical Prato reaction, is an effective and facile approach to regulate the electronic structure and molecular dynamics of EMFs. In this work, novel pyrrolidine products of Sc3N@C80 and Sc3C2@C80 were successfully synthesized via Prato reactions using L-cysteine and paraformaldehyde. Structure characterizations demonstrated that two regioisomers with a [5,6] and a [6,6] cycloaddition on the Ih-C80 cage were obtained both for Sc3N@C80 and Sc3C2@C80. Besides, the [6,6]-monoadduct of Sc3N@C80 was thermally stable while the [5,6]-monoadduct exhibited a retro-cycloaddition ability to recover the pristine Sc3N@C80. Electrochemical measurements revealed that the redox potential of Sc3N@C80 could be tuned via such exohedral modifications. Furthermore, the paramagnetic property and internal dynamics of the encapsulated Sc3C2 cluster of Sc3C2@C80 can be well-regulated by controlling the spin density of the molecule. The present work could provide a new approach to regulate the electronic and/or spin structure of EMFs.