Yufei Guo,Liqiang Zhang,Changhe Du,Yange Feng,Di Yang,Zhitao Zhang,Min Feng,Yong Wan,Daoai Wang
Triboelectric nanogenerators (TENGs) with sliding-mode have developed rapidly in the field of energy harvesting and sensing. However, its surface wear and low electric output performance usually limit its applicability. Herein, a mixture of hexadecane with onion-like carbon (OLC) lubricant is added to the interface between polytetrafluoroethylene (PTFE) film and steel to enhance the triboelectrical and tribological performance . During dry friction , the friction pair is severely worn and the current output decreases gradually with the transfer of a large amount of PTFE debris in a short period. The introduction of hexadecane partly resolves the problems such as friction and wear with the reduction in the transfer of PTFE material. However, the current output decreases gradually during the friction process because there is still some slight material transfer in the interface. The electrical output of TENG is further enhanced with the addition of OLC, and its tribological properties are comparable or better than oil-based TENG. The short-circuit currents (I sc ) of the oil-based TENG and the oil-OLC-based TENG are 1.5 times and 5 times that of the TENG in the dry friction state, respectively. Also, the coefficient of friction (COF) of oil-OLC-based TENG is reduced by about 75.3% compared with dry friction state. The oil-OLC-based lubricant reduces the transfer film formation, increases the effective contact area, and squeezes the air at the interface. Also, part of the OLC rolls between the two friction layers, forming a "micro-bearing", further reducing the generation of transfer film. This study provides a novel way to improve the output efficiency and prolong the service life of TENG.
Yi Zhang,Jianhong Lan,Yike Xu,Yuanyuan Yan,Weifeng Liu,Xuguang Liu,Shaonan Gu,Jiadong Zhou,Meiling Wang
Zeolitic imidazolate framework-67 (ZIF-67) has been widely used as a precursor to developing efficient PtCo alloy catalysts for hydrogen evolution reaction (HER). However, traditional in-situ pyrolysis strategies involve complicated interface structure modulating processes between ZIF-67 and Pt precursors, challenging large-scale synthesis. Herein, a “pyrolysis etching-confined pyrolysis” approach is developed to design confined PtCo alloy in porous frameworks of onion carbon derived from ZIF-67. The confined PtCo alloy with Pt content of only 5.39 wt% exhibits a distinct HER activity in both acid (η 10 : 5 mV and Tafel: 9 mV dec −1 ) and basic (η 10 : 33 mV and Tafel: 51 mV dec −1 ) media and a drastic enhancement in stability. Density functional theory calculations reveal that the strong electronic interaction between Pt and Co allows favorable electron redistribution, which affords a favorable hydrogen spillover on PtCo alloy compared with that of pristine Pt(1 1 1). Operational electrochemical impedance spectroscopy demonstrates that the Faraday reaction process is facilitated under acidic conditions, while the transfer of intermediates through the electric double-layer region under alkaline conditions is accelerated. This work not only offers a universal route for high-performance Pt-based alloy catalysts with metal–organic framework (MOF) precursors but also provides experimental evidence for the role of the electric double layer in electrocatalysis reactions.
Hydrogen peroxide (H 2 O 2 ) electrosynthesis through oxygen reduction reaction (ORR) is drawing worldwide attention, whereas suffering seriously from the sluggish oxygen evolution reaction (OER) and the difficult extraction of thermodynamically unstable H 2 O 2 . Herein, we present an electrosynthesis protocol involving coupling ORR-to-H 2 O 2 with waste polyethylene terephthalate (PET) upcycling and the first H 2 O 2 conversion strategy. Ni-Mn bimetal- and onion carbon-based catalysts are designed to catalyze ORR-to-H 2 O 2 and ethylene glycol electrooxidation with the Faradaic efficiency of 97.5% (H 2 O 2 ) and 93.0% (formate). This electrolysis system runs successfully at only 0.927 V to achieve an industrial-scale current density of 400 mA cm −2 , surpassing all reported H 2 O 2 electrosynthesis systems. H 2 O 2 product is upgraded through two downstream routes of converting H 2 O 2 into sodium perborate and dibenzoyl peroxide. Techno-economic evolution highlights the high gross profit of the ORR || PET upcycling protocol over HER || PET upcycling and ORR || OER. This work provides an energy-saving methodology for the electrosynthesis of H 2 O 2 and other chemicals.
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