An efficient hierarchical solar water evaporator with polypyrrole-enabled light trapping on surface-carbonized pulp foam matrix

Carbonized materials have been reported as potential candidates for the application of solar water evaporation due to their low cost and easy availability. However, the unregulatable internal structures of these evaporators are usually not conducive for achieving high evaporation rates. Herein, foam material with artificial three-dimensional configurations was selected in our work to combine with surface carbonization for improving the evaporation performance. By utilizing pulp foam (PF) as raw material, our present work proposes an easy-fabricated hierarchical evaporator design composed of an upper carbonized pulp foam (CPF) layer and a bottom pristine PF matrix layer. Deposition of polypyrrole (PPy) particles on the carbonized layer was applied for further enhancement on the evaporation performance based on light trapping effect. As a result, the CPF-2PPy evaporator fabricated in our work could achieve an average evaporation rate of 2.56 kg m−2 h−1 under 1.0 sun illumination during a 10-cycle indoor evaporation experiments. Our work reports a convenient approach to fabricate a highly efficient solar water evaporator based on the simple surface carbonization of PF and the light trapping effect produced by PPy nanoparticles deposited on it. •Cellulose-derived pulp foam was used as the raw material for producing evaporators.•Hot-plate carbonization produced hierarchical structure for the evaporators.•Light trapping effect enabled by PPy deposition accelerated the evaporation.•Average evaporation rate of 2.56 kg m−2 h−1 was achieved during cyclic evaporation.