Research Article Online first
Hydrogen spillover bridged dual nano-islands triggered by built-in electric field for efficient and robust alkaline hydrogen evolution at ampere-level current density
Nano Research
Published: 22 March 2024

Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges, particularly for the construction of hydrogen evolution reaction (HER) catalysts operating at ampere-level current density. Herein, the unique Ru and RuP2 dual nano-islands are deliberately implanted on N-doped carbon substrate (denoted as Ru-RuP2/NC), in which a built-in electric field (BEF) is spontaneously generated between Ru-RuP2 dual nano-islands driven by their work function difference. Experimental and theoretical results unveil that such constructed BEF could serve as the driving force for triggering fast hydrogen spillover process on bridged Ru-RuP2 dual nano-islands, which could invalidate the inhibitory effect of high hydrogen coverage at ampere-level current density, and synchronously speed up the water dissociation on Ru nano-islands and hydrogen adsorption/desorption on RuP2 nano-islands through hydrogen spillover process. As a result, the Ru-RuP2/NC affords an ultra-low overpotential of 218 mV to achieve 1.0 A·cm−2 along with the superior stability over 1000 h, holding the great promising prospect in practical applications at ampere-level current density. More importantly, this work is the first to advance the scientific understanding of the relationship between the constructed BEF and hydrogen spillover process, which could be enlightening for the rational design of the cost-effective alkaline HER catalysts at ampere-level current density.

Communication Online first
Efficient ammonia production over eg-occupancy-optimized perovskite electrocatalysts
Nano Research
Published: 07 March 2024

Renewable-energy-driven nitrate (NO3) electroreduction to ammonia (NH3) (NERA) has been an attractive technology for decarbonizing NH3 production and wastewater treatment. Improving NERA efficiency requires electrocatalysts that are earth-abundant and show fantastic performance. Here we report a semiempirical activity descriptor of eg occupancy (of surface B-site cations) for identifying inexpensive perovskite oxides with extremely high efficacy toward NERA. We establish the descriptor by systematic investigations of more than 10 perovskite oxides. These investigations demonstrate that their intrinsic NERA activities display a volcano-shaped dependence on eg occupancy and the optimized intrinsic activities are accessible at near-1 eg occupancies. This could plausibly be attributed to the favorable overlaps between surface adsorbates and vertically-oriented eg orbitals. More importantly, utilizing this descriptor, we predict a highly active, selective, and durable NERA electrocatalyst with a composition of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF). Because of its close-to-1 eg occupancy (i.e. ~ 1.2), the BSCF features a superior NH3 production rate of 0.12 g·h−1·mgcat.−1 (Faradaic efficiency of 97.8%) that is at top of the volcano plot, and substantially outperforms most NERA electrocatalysts reported in literature.

Research Article Issue
Crown ether interlayer-modulated polyamide membrane with nanoscale structures for efficient desalination
Nano Research 2023, 16 (5): 6153-6159
Published: 18 November 2022

Nanoscale thin-film composite (TFC) polyamide membranes are highly desirable for desalination owing to their excellent separation performance. It is a permanent pursuit to further improve the water flux of membrane without deteriorating the salt rejection. Herein, we fabricated a high-performance polyamide membrane with nanoscale structures through introducing multifunctional crown ether interlayer on the porous substrate impregnated with m-phenylenediamine. The crown ether interlayer can reduce the diffusion of amine monomers to reaction interface influenced by its interaction with m-phenylenediamine and the spatial shielding effect, leading to a controlled interfacial polymerization (IP) reaction. Besides, crown ether with intrinsic cavity is also favorable to adjust the IP process and the microstructure of polyamide layer. Since the outer surface of the nanocavity is lipophilic, crown ether has good solvency with the organic phase, thus attracting more trimesoyl chloride molecules to the interlayer and promoting the IP reaction in the confined space. As a result, a nanoscale polyamide membrane with an ultrathin selective layer of around 50 nm is obtained. The optimal TFC polyamide membrane at crown ether concentration of 0.25 wt.% exhibits a water flux of 61.2 L·m−2·h−1, which is 364% of the pristine TFC membrane, while maintaining a rejection of above 97% to NaCl. The development of the tailor-made nanoscale polyamide membrane via constructing multifunctional crown ether interlayer provides a straightforward route to fabricate competitive membranes for highly efficient desalination.

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