With the advancement of civilization, water purification, as well as management and disposal of ever-increasing municipal solid waste (MSW), and e-waste, have become global concerns. To address these issues in a sustainable way, a 3D solar evaporator has been proposed in this paper by repurposing recycled paper from MSW in the form of egg trays and waste dry toner (e-waste) using a facile fabrication method. The unique 3D porous structure, fibrous surface, superior water absorbing capability as well as low thermal conductivity of wastepaperderived egg trays make them an excellent candidate for an efficient solar evaporator, while the waste toner powder coating significantly enhances the optical absorbance capacity. Under 1 sun illumination, the proposed solar evaporator demonstrates an excellent evaporation rate and efficiency of 1.3 kg/m 2 h and 78.5%, respectively. Moreover, the competitive advantage of the 3D structure in collecting solar irradiance at various light incident angles in comparison to a 2D structure, excellent cycle stability, low processing temperature, and the use of low-cost waste materials enable its use for large-scale water purification systems.

The nonlinear optical (NLO) properties of two-dimensional (2D) materials are fascinating for fundamental physics and optoelectronic device development. However, relatively few investigations have been conducted to establish the combined NLO activities of a 2D material. Herein, a study of numerous NLO properties of 2D gallium sulfide (GaS), including second-harmonic generation (SHG), two-photon excited fluorescence (TPEF), and NLO absorption are presented. The layer-dependent SHG response of 2D GaS identifies the noncentrosymmetric nature of the odd layers, and the second-order susceptibility (χ2) value of 47.98 pm/V (three-layers of GaS) indicates the superior efficiency of the SHG signal. In addition, structural deformation induces the symmetry breaking and facilitates the SHG in the bulk samples, whereas a possible efficient symmetry breaking in the liquid-phase exfoliated samples results in an enhancement of the SHG signal, providing prospective fields of investigation for researchers. The generation of TPEF from 800 to 860 nm depicts the two-photon absorption characteristics of 2D GaS material. Moreover, the saturable absorption characteristics of 2D GaS are realized from the largest nonlinear absorption coefficient (β) of −9.3 × 103, −91.0 × 103, and −6.05 × 103 cm/GW and giant modulation depths (T s ) of 24.4%, 35.3%, and 29.1% at three different wavelengths of 800, 1066, and 1560 nm, respectively. Hence, such NLO activities indicate that 2D GaS material can facilitate in the technical advancements of future nonlinear optoelectronic devices.

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