23 Apr 13:56
by Shuangjian Yu,
Siwu Wu,
Shifeng Fang,
Zhenghai Tang,
Liqun Zhang,
Baochun Guo
A brand-new design concept of a skeletal network is pioneered to realize the upcycling of conventional vulcanizates. The resultant materials, integrated with the superior strength/elasticity of conventional vulcanizates and the extrudable reprocessability of thermoplastics, can exploit a feasible alternative toward a new generation of thermoplastic vulcanizates.
Abstract
Upcycling of cross-linked rubbers is pressing. The introduction of dynamic covalent bonds into the networks is a popular tactic for recycling thermosetting polymers, but it is very challenging to integrate engineering performance and continuous yet stable reprocessability. Based on traditional rubber formulations, herein, a straightforward strategy is presented for constructing a skeletal network (SN) through interfacial crosslinking and percolation of rubbery granules in a rubber matrix. Rapid exchange reactions involving dynamic interfacial sulfides realize repeated “fragmentation and healing” in the solid-state and consequent reconfiguration of the SN topology of the elastomer, thus endowing the resultant SN elastomer with continuous yet stable re-extrudability. These SN elastomers with hierarchical structures exhibit high gel contents, high resilience, low creep, and reinforcibility competitive to traditional vulcanizates. Specifically, SN elastomers exhibit better overall performance than commercial thermoplastic vulcanizates (TPVs) materials. Overall, a new concept of thermoplastic vulcanizates is proposed, which will promote the sustainable development of rubbers.
23 Apr 13:56
by Kai Wang,
Jinhui Zhou,
Mingzi Sun,
Fangxu Lin,
Bolong Huang,
Fan Lv,
Lingyou Zeng,
Qinghua Zhang,
Lin Gu,
Mingchuan Luo,
Shaojun Guo
A class of Cu-doped Ru/RuSe2 heterogeneous nanosheets for highly efficient hydrogen evolution reaction (HER) in alkaline media is designed and synthesized. The superior HER performance is attributed to a synergistic effect of the unique heterogeneous interface structure and Cu doping, which leads to the optimized H and H2O adsorption to boost hydrogen evolution catalysis.
Abstract
Ruthenium chalcogenide is a highly promising catalytic system as a Pt alternative for hydrogen evolution reaction (HER). However, well-studied ruthenium selenide (RuSe2) still exhibits sluggish HER kinetics in alkaline media due to the inappropriate adsorption strength of H and H2O. Herein, xx report a new design of Cu-doped Ru/RuSe2 heterogeneous nanosheets (NSs) with optimized H and H2O adsorption strength for highly efficient HER catalysis in alkaline media. Theoretical calculations reveal that the superior HER performance is attributed to a synergistic effect of the unique heterointerfaced structure and Cu doping, which not only optimizes the electronic structure with a suitable d-band center to suppress proton overbinding but also alleviates the energy barrier with enhanced H2O adsorption. As a result, Cu-doped heterogeneous Ru/RuSe2 NSs exhibit a small overpotential of 23 mV at 10 mA cm−2, a low Tafel slope of 58.5 mV dec−1 and a high turnover frequency (TOF) value of 0.88 s−1 at 100 mV for HER in alkaline media, which is among the best catalysts in noble metal-based electrocatalysts toward HER. The present Cu-doped Ru/RuSe2 NSs interface catalyst is very stable for HER by showing no activity decay after 5000-cycle potential sweeps. This work heralds that heterogeneous interface modulation opens up a new strategy for the designing of more efficient electrocatalysts.