Highly efficient clean water production: Reduced graphene oxide/ graphitic carbon nitride/wood

•Solar steam fluxes of 4.78 kg m−2h−1 by RGO/g-C3N4/wood under 3 sun.•Fully degradation of RB5, azo dye, by RGO/g-C3N4/wood under solar light.•Completely sorption of Pb (II) from aqueous solutions by RGO/g-C3N4/wood. Herein, a multifunction system was designed for water purification. Reduced graphene oxide (RGO) and graphitic carbon nitride (g-C3N4) nanosheets were deposited on poplar wood to prepare the double-layer multifunctional nanoplatforms for use in a solar steam generation (SSG) of seawater, photodegradation of an organic pollutant (RB5 azo dye), and sorption of Pb (II) from aqueous solutions. The solar steam flux of 4.78 kg m−2h−1 was achieved by RGO/g-C3N4/wood under 3 kW m−2, respectively. High performance of RGO/g-C3N4/wood device is due to the broadband harvesting of solar energy of RGO/g-C3N4 as a photothermal material and channeled structure, low thermal conductivity (TC), and hydrophilic nature of wood as a substrate. The durability test showed a stable performance of RGO/g-C3N4/wood photoabsorber for 30 cycles. The total cost of solar water evaporation of RGO4/g-C3N4/wood was calculated to be 0.08 USD/(cm3 h−1) which is significantly more cost-effective than other previous reports. RGO/g-C3N4/wood as an efficient photocatalyst degraded completely RB5. g-C3N4 plays the main role in the photodegradation of dye and RGO improves its photocatalytic performance by slowing the electron/hole recombination. Also, RGO/g-C3N4/wood as a sorbent adsorbed completely Pb (II) from aqueous solutions.