▎ 摘　　要

Introducing heteroatom active sites and functional units is essential for achieving high-performance graphene in potential applications of optoelectronic devices and sustainable solar-heat energy conversion/storage. Density functional theory calculations with long-range van der Waals effects (vdW-DF2) were performed to study the electronic structures and energy storage/release of graphene through sulfur (S)-doping and physisorption of pc-conjugated photo responsive molecules, trans/cis-azobenzene (AB) derivatives with an electron-donating substituent group and trans/cisstilbene (ST), respectively. With the increase of the S-doping concentration from 0.4 to 0.8 atom/nm(2), the band gap of graphene exhibits the enhanced metallic characteristics with a direct-to-indirect transition. Although AB and ST molecules have different unsaturated bridge bonds, -N=N- versus -CH= CH-, physisorption of these two photoresponsive molecules onto the graphene can both broaden the band gap to about 0.02 eV, as a result of the pi-pi interfacial interactions. Under the exposure to the solar light, the facile trans-to-cis isomerization of the AB (ST) molecule adsorbed onto graphene renders the energy storage of about 1.04 eV (0.49 eV) in each molecule. The noncovalent physisorption of trans/cis-AB molecules onto graphene is unexpectedly more favorable to energy storage than that of covalent binding. In addition, a multifunctional graphene model, with the combination of both S -doping and physisorption of photoresponsive moelcules, could not only open a band gap of about 0.27 eV but also induce energy storage of 0.84 eV per molecule via the conformational change from trans-to cis-AB isomer. Strong charge localization at the S dopant may become the active sites for catalysis and energy storage, and meanwhile, photoactive adsorbates could further promote the energy conservation and release.