Highly Efficient Osmotic Energy Harvesting in Charged Boron‐Nitride‐Nanopore Membranes

Abstract

Recent studies of the high energy‐conversion efficiency of the nanofluidic platform have revealed the enormous potential for efficient exploitation of electrokinetic phenomena in nanoporous membranes for clean‐energy harvesting from salinity gradients. Here, nanofluidic reverse electrodialysis (NF‐RED) consisting of vertically aligned boron‐nitride‐nanopore (VA‐BNNP) membranes is presented, which can efficiently harness osmotic power. The power density of the VA‐BNNP reaches up to 105 W m−2, which is several orders of magnitude higher than in other nanopores with similar pore sizes, leading to 165 mW m−2 of net power density (i.e., power per membrane area). Low‐pressure chemical vapor deposition technology is employed to uniformly deposit a thin BN layer within 1D anodized alumina pores to prepare a macroscopic VA‐BNNP membrane with a high nanopore density, ≈108 pores cm−2. These membranes can resolve fundamental questions regarding the ion mobility, liquid transport, and power generation in highly charged nanopores. It is shown that the transference number in the VA‐BNNP is almost constant over the entire salt concentration range, which is different from other nanopore systems. Moreover, it is also demonstrated that the BN deposition on the nanopore channels can significantly enhance the diffusio‐osmosis velocity by two orders of magnitude at a high salinity gradient, resulting in a huge increase in power density.

Nanofluidic osmotic power generators – advanced nanoporous membranes and nanochannels for blue energy harvesting

“…The functionalization of nanochannels with different molecular systems has been one of the most applied approaches to obtain a high performance in multi-channel membranes. 169,218,219,[250][251][252][253][254][255] Liu et al developed a highly selective nanoporous membrane based on the integration of the MOF UiO-66-NH 2 onto the surface of a highly ordered AAO membrane (UiO-66-NH 2 -AAO). 224 The composite membrane was created by in situ growth of the MOF UiO-66-NH 2 onto a presynthesized AAO membrane modied with 3-triethoxysilylpropylamine (APTES).…”

Direct growth of hexagonal boron nitride on non-metallic substrates and its heterostructures with graphene

“…Recently, attempts have been made to directly grow h-BN sheets on insulating/dielectric substrates like SiO 2 /Si, Si 3 N 4 /Si, silicon (111), quartz, sapphire, single crystal diamond, and 6H-SiC by employing techniques such as: low-pressure thermal chemical vapor deposition (CVD) ( Behura et al., 2015 , 2017 ; Jang et al., 2016 ; Pendse et al., 2021 ; Tay et al., 2015 ; Wang et al., 2020 ), cold wall chemical vapor deposition ( Ahmed et al., 2016 ), metal organic chemical vapor deposition (MOCVD) ( Majety et al., 2013 ; Vangala et al., 2018 ), molecular beam epitaxy (MBE) ( Page et al., 2019 ) ( Vuong et al., 2017 ), ion beam sputtering deposition (IBSD) ( Gao et al., 2019 ), metal organic vapor phase epitaxy (MOVPE) ( Chugh et al., 2018 ; Yang et al., 2018 , 2020 ), and atomic layer deposition (ALD) ( Lee et al., 2020 ; Park et al., 2017 ). Here we sift through some key techniques and related mechanistic principles to nucleate h-BN crystals on dielectric substrates.…”

“…Few to multilayered h-BN films with thickness ranging from 2 to 25 nm were grown through the random nucleation on dielectric substrates. A series of experimental reports during 2015-2021 described the growth kinetics and nucleation phenomena for the direct growth of h-BN layers on SiO 2 /Si, Si 3 N 4 /Si, Si, and Al 2 O 3 substrates ( Behura et al., 2015 , 2017 ; Pendse et al., 2021 ; Wang et al., 2020 ). Low-pressure CVD was employed at a controlled hydrogen environment and at a varied temperature of 700-1100°C using ammonia borane as a solid precursor.…”

A Comprehensive Review on the Applications of Boron Nitride Nanomaterials in Membrane Fabrication and Modification

“…In addition, BN-based membranes are investigated in other membrane processes and seemed to be suitable for ionic transportation. The recent investigation related to the energy harvesting application of membranes was conducted by Pendse et al 170 They theorized that BNNTs could be a promising material for reverse electrodialysis (RED) devices used for power generation. This potential arises from the high surface charge property of BNNTs that provide a higher concentration of salt ion, which leads to give osmotic pressure discrepancy.…”

“…203 In a recent study, it was emphasized that a nanofluid device containing a single BNNT could be important for RED due to the high surface charge on the BN surface. Pendse et al 170 proposed that the BN-based membrane has excellent potential for RED applications, and can accomplish the low power density limitation of RED systems based upon ion exchange membranes or nanofluidic channel devices. Power generation at different pH values and salt concentrations in BN-based membranes has been investigated.…”