Seawater-flow- and -evaporation-induced electricity generation
holds significant promise in advancing next-generation sustainable
energy technologies. This method relies on the electrokinetic effect
but faces substantial limitations when operating in a highly ion-concentrated
environment, for example, natural seawater. We present herein a novel
solution using calcium-based metal–organic frameworks (MOFs,
C12H6Ca2O19·2H2O) for seawater-evaporation-induced electricity generation.
Remarkably, Ca-MOFs show an open-circuit voltage of 0.4 V and a short-circuit
current of 14 μA when immersed in seawater under natural conditions.
Our experiments and simulations revealed that sodium (Na) ions selectively
transport within sub-nanochannels of these synthetic superhydrophilic
MOFs. This selective ion transport engenders a unipolar solution flow,
which drives the electricity generation behavior in seawater. This
work not only showcases an effective Ca–MOF for electricity
generation through seawater flow/evaporation but also contributes
significantly to our understanding of water-driven energy harvesting
technologies and their potential applications beyond this specific
context.