Fig. 3: Mechanism of the solar steam enhancement on the biomimetic 3D solar evaporator.

a Infrared image of the biomimetic 3D evaporator in dry state in darkness. b, c Time sequence of infrared captures during the water upward spreading process. d Infrared image of the dynamic equilibrium state of the solar steam generation process. e Temperature profiles along the biomimetic 3D evaporator surface (red line) under one sun illumination, with 3D columnar structure (orange line), 2D plane (blue line), and pure water (black line) as controls. Inset is the equilibrium infrared image on the 3D columnar structure under one sun illumination. Temperature range is 15–35 °C. f Numerical simulation result of the steam diffusion flux at the water/steam interface under one sun illumination. g Temperature profiles along the biomimetic 3D structure surface (red line) in darkness, with 3D columnar structure (orange line), 2D plane (blue line), and pure water (black line) as controls. h Numerical simulation result of the steam diffusion flux at the water/steam interface in darkness. i The mass change and energy efficiency of water on the biomimetic 3D evaporators with different H/D ratios. Orange, black, and blue lines represent the water evaporation rate in darkness, the solar steam generation rate under one sun illumination, and the energy efficiency under one sun illumination, respectively. The error bars in the evaporation rate result from errors in the mass-change measurements. The error bars in the efficiency values resulted from errors in the measurement of solar illumination power, the evaporation rate and the interface temperature. Each error bar represents the deviation from at least five data points. j Temperature differences between the bottom and the apex surface temperature with the variation of H/D ratios. Black and orange lines represent the temperature difference under one sun illumination and in darkness, respectively. Insets are equilibrium infrared images on biomimetic 3D evaporators with different H/D ratios under one sun illumination. The error bars resulted from errors in the measurement of the surface temperature. Each error bar represents the deviation from at least five data points.