Fig. 2: Power generation performance and evaporation characteristics of the IENG.

a Open-circuit voltage per unit area of the IH, the IH with MWNTs and the IENG. b Short-circuit currents per unit area for the IH, the IH with MWNTs and the IENG. c Water evaporation rates of bulk water and the IENG with different layers in over 1 h. d Energy conversion efficiencies and water evaporation rates of bulk water and the IENG with different layers. The lengths, widths and heights were 10 mm, 10 mm and 20 mm, respectively. The error bars represent standard deviations.