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Proposed mechanism of BiVO 4 /CN-QA. [Display omitted] • Quinolinic acid (QA) doped g-CN (CN-QA) was developed via facile thermal approach. • Different samples of BiVO 4 /CN-QA with high stability were prepared via hydrothermal method. • Remarkable enhanced photocatalytic H 2 and O 2 evolution was achieved using these catalysts via overall water splitting. • A dual synergetic mechanism on BiVO 4 /CN-QA has been proposed. The development of copolymerized carbon nitride (CN)-based photocatalysts may support advances in photocatalytic overall water splitting. However, the recombination of charge carriers is the main bottleneck that reduces its overall photocatalytic activity. To overcome this problem, the construction of heterojunction technology has emerged as an effective approach to reduce the charge carrier recombination, thereby improving charge separation and transport efficiency. In this work, an innovative heterojunction was prepared between Quinolinic acid (QA) modified CN (CN-QA x) and novel nanorod-shaped bismuth vanadate (BiVO 4) (BiVO 4 /CN-QA x) for overall water splitting through a simple in-situ solvent evaporation technique. The obtained results show that the synthesized samples have efficient and improved activities for releasing H 2 (862.1 μmol/h) and O 2 (31.58 μmol/h) under visible light irradiation. Furthermore, an exceptional apparent quantum yield (AQY) of 64.52 % has been recorded for BiVO 4 /CN-QA 7.0 at 420 nm, which might be due to the substantial isolation of photoinduced charge carriers. Therefore, this work opens up a new channel toward efficient CN-based photocatalysts in the sustainable energy production processes. [ABSTRACT FROM AUTHOR]

• Optoelectronic properties of phenylimidazo-pyridine derivatives are analysed at molecular and bulk scales. • Effect of indol, phenyl and anthracenyl on properties of interests was examined. • Hybrid functionals are accurate to reproduce experimental λ abs and λ emi than LC. • The n- or p-type charge transport nature has been explored. • FMOs, IP, EA, intrinsic mobility, DOS, dielectric constant displayed them as multifunctional materials. Various optoelectronic and charge transfer properties of 3-(1H-indol-3-yl)-1-phenylimidazo[1,5-a]pyridine (Comp 1), 1,3-diphenylimidazo[1,5-a]pyridine (Comp 2), and 3-(Anthracen-9-yl)-1-phenylimidazo[1,5-a]pyridine (Comp 3) have been explored at the molecular and solid state bulk level. The absorption and emission spectra (λ abs and λ emi) were calculated by time domain B3LYP/6-311G*, CAM-B3LYP/6-311G*, LC-BLYP/6-311G* and PBE0/6-311G* levels. The hybrid functionals B3LYP and PBE0 successfully reproduced experimental λ abs and λ emi more accurately than the long-range corrected functionals. Effect of indol, phenyl and anthracenyl moieties on various properties of interests has been explored. The indol and phenyl units lead to smaller hole reorganization energies and greater transfer integrals resulting superior hole intrinsic mobility for Comps 1 and 2. The substitution of anthracenyl moiety at phenylimidazo[1,5-a]pyridine core increase the electron affinity and electron transfer integrals while decrease the electron reorganization energy. The n- or p-type charge transfer nature of Comp 3 or Comps 1 and 2 has been explored, respectively. The frontier molecular orbitals, ionization potential, electron affinity, reorganization energy, transfer integral, intrinsic mobility, density of states, dielectric constant, extinction coefficient, refractive indices, reflectivity and conductivity shown that imidazo[1,5-a]pyridine derivatives would be efficient materials to be used in multifunctional organic semiconductor devices. [ABSTRACT FROM AUTHOR]