Graphite powder/semipermeable collodion membrane composite for water evaporation

Abstract Water evaporation, a promising and environmentally friendly technology driven by local hot spots on the water-air interface, is an efficient way to utilize solar energy. Herein, we present a novel laminar solar absorber consisting of graphite powder (GP) and a semipermeable collodion membrane (SCM) as an integrated structural system for highly efficient water evaporation. The GP/SCM composite can efficiently convert the absorbed solar energy to heat energy, e.g., the 8 mg-GP/SCM (i.e., the GP/SCM with 8 mg GP added) enables water evaporation with high efficiency of 56.8% under 1.5 kW/m 2 irradiation and 65.8% under 3 kW/m 2 irradiation, respectively. Cycling tests verify that the GP/SCM could retain stable water evaporation performance over 20 cycles under the same conditions. Contrast experiments show that the other carbon-containing solar-absorbers, such as acetylene black (AB) and graphene nanoplates (GNPs) in SCM, display relatively low evaporation efficiency of 41.4% and 36.7%, respectively, under the simulated solar irradiation with a light density of 1.5 kW/m 2 . The laminar GP/SCM composite obtained in our work is low-cost, easy-to-prepare, recyclable, and highly efficient in its photothermal performance, so that it distinctly contributes to water evaporation.