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In the independent state, PA and GO are too far away from each other to induce any interactions and energy lowering. Accordingly, the energy of the independent state is calibrated to zero as the energy benchmark, signified by pink dotted line. In the combined state, however, PA and GO draw near to form the stable framework PA-GO driven by energy lowering. Structural diagram of PA, GO and PA-GO are presented as inset. [Display omitted] • Phytic acid functionalized graphene oxide (PA-GO) was facilely fabricated. • C 6 H 6 O 24 P 6 12- is the dominant species of phytic acid in PA-GO fabrication system. • Combination mechanism based on electron transfer induced energy lowering for PA-GO. • PA-GO exhibits high adsorption capacity for ionic dyes in five consecutive cycles. Phytic acid functionalized graphene oxide (PA-GO) has encouraging application in environmental treatment. Herein, structure of PA-GO fabricated by hydrothermal method was inspected. Firstly, the aqueous species distribution and ionization states of phytic acid (PA) and graphene oxide (GO) under varying pH was analyzed according to equilibrium thermodynamics to clarify the primary interacting species involved in PA-GO fabrication. Secondly, the hard-soft acid-base (HSAB) theory and spectroscopic characterizations (XPS, FTIR, Raman, UV–Vis and fluorescent spectra) were employed to elucidate the plausible interactions existing in PA-GO. Thermodynamic deduction indicates, C 6 H 6 O 24 P 6 12- is the dominant species of PA, while –OH and –COO- are the dominant state of graphene oxide groups in PA-GO fabrication system. HSAB theory illuminates, the primary interactions occurs between deprotonated oxygen O(O-) and bridged oxygen O(-O-) of phytic acid with hydroxyl group O(Ar-OH) and π electron of graphene oxide. Moreover, electron flows from GO towards PA to induce energy lowering whereby PA-GO is stabilized. HSAB theory prediction was substantiated by spectroscopic analyses. Furthermore, PA-GO efficiently removes ionic dyes in five consecutive cycles with high adsorption capacity. This work may shed light on the fabrication chemistry of PA-GO framework serving as a potential adsorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ growth of p-type Ag 2 O on n-type Bi 2 O 2 S surface was achieved. • The heterostructure enhanced the activity of NIR light driven CO 2 photoreduction. • Intimate interfacial contact and heterostructure contributed to the charge transfer. • Ag 2 O/Bi 2 O 2 S exhibited an outstanding ability for adsorption and activation of CO 2. • The reaction mechanism was unveiled based on the experiments and DFT calculations. Photocatalytic converting CO 2 into organic carbon resources holds promise for achieving the utilization of CO 2 resources and the development of clean energy. However, the low utilization efficiency of solar energy and poor separation efficiency of photo-generated carriers limit the application of photocatalytic CO 2 reduction. Herein, Ag 2 O/Bi 2 O 2 S p-n heterojunction photocatalyst (xAO/BOS) was constructed by anchoring Ag 2 O on the surface of Bi 2 O 2 S through in-situ synthesis. The novel 27 %AO/BOS photocatalyst shows the enhanced photocatalytic CO 2 reduction performance with 14.49 μmol g−1 of CO yield and 12.06 μmol g−1 of CH 4 yield after 120 min of NIR light irradiation. The formed p-n heterojunction in 27 %AO/BOS photocatalyst by the in-situ synthesis contributes to facilitating the separation and transfer of photo-generated carriers and improving the adsorption and activation of CO 2. The composite still exhibits excellent photocatalytic cycling stability, and Ag0 species are produced in the photocatalytic CO 2 reduction reaction owing to the in-situ photoreduction of Ag 2 O. Based on the experimental analyses and theoretical calculations, the proposed mechanism for the improved photocatalytic CO 2 reduction activity over in-situ synthesis of 27 %AO/BOS p-n heterojunction photocatalyst is finally given. This work paves a promising way to construct effective NIR light-responsive photocatalysts for CO 2 photoreduction. [ABSTRACT FROM AUTHOR]