Fig. 1. Number of yearly publications with the subject of “graphene & photocatal*” since 2010. (Using Web of Science, date of search: May 27, 2021.)

Fig. 2. Illustration of synthesis of GR-based composite photocatalysts oriented by roles of GR in photocatalysis.

Fig. 3. Numerous advantages of GR-based photocatalysis.

Fig. 4. Diagram of the optimization of dimensionality of GR (left) and GR-based hybrids with different structure (right).

Fig. 5. (a) TEM image of GQDs. Reprinted with permission from Ref. [104], Copyright 2017, Elsevier. (b) Diagram of bandgap structures of GQDs with different pore sizes. Reprinted with permission from Ref. [105], Copyright 2016, American Chemical Society. (c) Diagram of bandgap structures of GQDs with different chemical groups. Reprinted with permission from Ref. [106], Copyright 2018, American Chemical Society. (d) TEM image of GNRs. (e) Photoinduced charge carrier transport process of CdS/GNR/Pt. (d,e) Reprinted with permission from Ref. [107], Copyright 2019, Wiley-VCH. (f) Diagram of photocatalytic mechanism of RhB degradation over N-GNRs/B-GR sheets. Reprinted with permission from Ref. [108], Copyright 2014, Royal Society of Chemistry.

Fig. 6. Diagram of charge transfer pathways of GR-based dual-cocatalysts system and different types of cocatalysts that coupled with GR.

Fig. 7. SEM images of blank ZnIn2S4 (a) and ZnIn2S4-GR composite (b). (a,b) Reprinted with permission from Ref. [116], Copyright 2014 Royal Society of Chemistry. (c) Illustration of synthesis process of Co-MOL@GO. TEM image (d) and AFM analysis (e) of Co-MOL@GO, (f) Time-resolved absorption spectra of blank RuPS, RuPS with triethanolamine, RuPS with Co-MOL@GO and RuPS with Co-MOF in acetonitrile with the excitation wavelength of 450 nm; (g) Proposed mechanism of photoreduction of CO2 over Co-MOL@GO. (c?g) Reprinted with permission from Ref. [70], Copyright 2021, Nature Publishing Group.

Fig. 8. (a) Diagram of synthesis process of Ni2P-FGR; (b) Diagram of Ni2P NSs synthesis utilizing FGR to reduce lattice strain during phosphating treatment; TEM image (c) and AFM analysis (d) of Ni2P-FGR; PL spectra (e) and LSV curves (f) of Ni2P and Ni2P-FGR; (g) Mechanism of visible light-driven H2 evolution over Ni2P-FGR-EY. Reprinted with permission from Ref. [59], Copyright 2018, Wiley-VCH.

Fig. 9. (a) Diagram of preparation method of RGA/AgBr/Ag hybrid; (b) PL spectra of bare AgBr and RGA/AgBr/Ag composite; (c) Possible mechanism of photocatalytic e. coli cells inactivation over RGA/AgBr/Ag hybrid. Reprinted with permission from Ref. [52], Copyright 2019, Elsevier.

Fig. 10. (a) Illustration of synthesis process of CdS-EGR and CdS-rGO; (b) Transient photocurrent responses of bare CdS, CdS-EGR and CdS-rGO composites. (a,b) Reprinted with permission from Ref. [60], Copyright 2018 Elsevier. (c) Diagram of synthesis method of rGO@EGR-EY aerogel; (d) Transient photocurrent responses of rGO-EY and rGO@EGR-EY aerogels. (c,d) Reprinted with permission from Ref. [54], Copyright 2018, Elsevier.

Fig. 11. (a) Diagram of preparation procedure of TNTAs@rGO/MoS2; (b) SEM images of top and side section, along with the diagram of TNTAs@rGO/MoS2; Photoactivity of H2 evolution (c) and transient photocurrent responses (d) of as-prepared samples; (e) Diagram of photocatalytic mechanism of H2 production over as-prepared catalysts. Reprinted with permission from Ref. [58], Copyright 2018, Wiley-VCH.

Fig. 12. (a) Diagram of fabrication method of transition metal hydroxides-GR composites; (b) SEM image of Ni(OH)2-10%GR; N2 adsorption-desorption isotherms (c), CO2 adsorption isotherms (d), CO2 TPD (e) and TRPL spectra (f) of as-prepared cocatalysts; (g) Probable mechanism of CO2 photoreduction over Ni(OH)2-10%GR. Reprinted with permission from Ref. [48], Copyright 2020, Nature Publishing Group.

Fig. 13. (a) Remaining concentration of MB after reaching adsorption equilibrium over P25-GR composites and photos of corresponding MB solution of each catalyst. Reprinted with permission from Ref. [165], Copyright 2010 American Chemical Society. Adsorption kinetics (b) and adsorption mechanism (c) of ZnFe2O4 and RG/ZF composites. (b,c) Reprinted with permission from Ref. [166], Copyright 2015, Elsevier.

Fig. 14. (a) Diagram of synthesis process of RTiC hydrogel; SEM images of RTiC hydrogel (b) and RTiC powder (c); (d) N2 adsorption-desorption isotherms of RTiC hydrogel and RTiC powder; FTIR spectra of GO/Ti3C2Tx (e) and GO (f) in different reaction times; (g) Raman spectra of RTiC hydrogel, Ti3C2Tx treated at 70 °C and RTiC hydrogel synthesized without NaHSO3; (h) Adsorption capacity of RTiC hydrogel and RTiC powder toward Cr (VI) and 4-NA. Reprinted with permission from Ref. [84], Copyright 2019, American Chemical Society.

Fig. 15. SEM images of rGO-ZnO hybrids with different rGO weight ratios: (a) 1 wt%; (b) 3 wt%; (c) 5 wt%; and (d) 10 wt%. (e) Probable mechanism for the formation of rGO-ZnO; DRS (f) and Tauc plots (g) of ZnO and rGO-ZnO composites. Reprinted with permission from Ref. [170], Copyright 2014, Royal Society of Chemistry.

Fig. 16. (a) TEM image of P25-GR; (b) DRS of P25 and P25-GR; (c) FTIR spectra of P25, GR and P25-GR. (a?c) Reprinted with permission from Ref. [165], Copyright 2010 American Chemical Society. (d) Schematic of fabrication method of AG/CdS composite; (e) Diagram for the amine functionalization of GO; (f) DRS of CdS and AG/CdS composites. (d?f) Reprinted with permission from Ref. [172], Copyright 2017, American Chemical Society.

Fig. 17. (a) DRS of ZnS and ZnS-GR composites with diverse loading amount of GR. Reprinted with permission from Ref. [46], Copyright 2012 American Chemical Society. (b) Diagram of preparation procedure of CNOMS/rGO; Band structure (c) and 3D charge density difference (d) of CNOMS/rGO hybrids; (e) Diagram of photocatalytic mechanism of H2 production over CNOMS/rGO. (b?e) Reprinted with permission from Ref. [44], Copyright 2018, Wiley-VCH.

Fig. 18. (a) Illustration of synthesis procedure of ZnO-rGO and ZnO-NanorGO; (b) Photoactivity over bare ZnO and ZnO-rGO hybrids toward Cr (VI) reduction; (c) Photoactivity over bare ZnO and ZnO-NanorGO hybrids toward Cr (VI) reduction; (d) The calculated electronic properties of rGO with various number of oxygen-containing groups; (e) VBM and CBM of GO with different ratios of -O- and -OH groups. Reprinted with permission from Ref. [41], Copyright 2016, American Chemical Society.