Optimized fabrication of hybrid hBN/SiN nanoporous membranes for osmotic power generation

Osmotic energy, the energy extracted by mixing two solutions with different salinities, has been receiving significant attention in the scientific community as a potential source of clean and renewable energy particularly promising for nano- and micro- power generators. A major impediment to exploiting osmotic energy is the poor efficiency of commercially available membranes for osmotic energy conversion. Nanoscale membranes with pores at or below 10 nm in diameter may provide sufficient power generation to make osmotic energy viable. Yet, currently no technology exists that can produce such membranes with sufficient control and scale. Here, leveraging our breakthrough tip-controlled local breakdown (TCLB) pore fabrication approach, we demonstrate high osmotic power density comparable to the density obtained with atomically thin 2D materials, yet with a scalable hybrid hBN/SiN membrane. In particular, the TCLB technique can produce pore arrays with a controlled spacing that yields optimum performance. Our work shows that the optimum membrane selectivity and overall power density is obtained with a pore spacing that balances the need for high pore density while maintaining a large extent of charged surface surrounding each pore.