Electronic structure modulation of metal-free graphdiyne for acidic oxygen evolution reaction

Developing high-performance metal-free electrocatalysts for acidic oxygen evolution reaction (AOER) is highly desirable but remains great challenge. Here we report a rationally substituting sp-C strategy for the synthesis of methyl- and hydrogen-substituted graphdiyne (MGDY, HGDY) nanowires arrays as 3D porous flexible metal-free electrodes for AOER. Methyl group in MGDY with stronger electron-pushing effect makes electrons around the acetylenic carbon atoms more delocalized, resulting in more uneven distributed surface charge, and higher intrinsic catalytic activities for AOER than HGDY, with the smaller overpotential of 406 mV at 10 mA cm−2 than HGDY and previously reported metal-free electrocatalysts. Our results reveal that the modulation of the electronic structure of GDY by selectively substituting sp-C allows for facilitating charge transfer kinetics, improving adsorption of reaction intermediate, and thereby accelerating the sluggish kinetics of AOER. This work provides us an ideal opportunity for studying the exact HER/OER mechanisms of metal-free carbon materials.

Word structure tunes electrophysiological and hemodynamic responses in the frontal cortex

As a morphological impoverished language, how does word structure impact Chinese lexical processing in the brain? To address this issue, the current study examined the temporal signatures and localizations in the human brain for morphological priming effect (compound/derivation constitute priming vs. non-morphological priming) and word structure modulation (derivation vs. compound) in light of EEG-fNIRS fusion. Whilst morphological priming effect was manifested in behavioral performance and left prefrontal hemodynamic responses, word structure effect was prominent drawing on behavioral, ERP, and fNIRS data. Chinese derivations elicited greater activation in the frontal cortex and engaged more distributed network than lexicalized compounds. The results were interpreted by the differing connection patterns between constitute morphemes within a given word structure from spreading activation perspective. Together, Chinese word structure effect showed a distinct pattern from the dual-route mechanism in alphabetic languages. Meanwhile, the current study for the first time identified dissociable behavioral and neurophysiological responses of Chinese derivations and coordinate compounds.