A metal-organic composite membrane with sub-2 nm pores was developed via interfacial coordination reaction in biphasic systems for the first time. Herein, tannic acid (TA) was dissolved in water, as aqueous phase; iron(III) acetylacetonate (Fe(acac) 3 ), used as Fe(III) source, was dissolved in n -hexane as organic phase. A detailed study was conducted to obtain the defect-free TA-Fe(III) separation layer, including the salt concentration in aqueous solution, pH of the aqueous solution and the ratio of TA to Fe(acac) 3 . The results indicated that the defect-free TA-Fe(III) composite membrane formed when the tris-complex (TA 3 -Fe(III)) was achieved. The optimal condition for preparing TA-Fe(III) composite membrane was using aqueous solution containing 0.4 M NaCl at pH = 6 with the ratio of TA to Fe(acac) 3 of 10. Different from the typical separation layer formed on the membrane surface by interfacial polymerization, the TA-Fe(III) separation layer was formed in the pores of the substrate, which is attributed to the higher diffusion coefficient of Fe(acac) 3 from organic phase to aqueous phase. This work provided a novel strategy to fabricate metal-organic composite membrane with sub-2 nm pores; meanwhile, the new-prepared membrane shows a high Na 2 SO 4 rejection of 97.3% with the water permeance of 8.6 L m −2 h −1 bar −1 , and a high VB 12 rejection of 97.6%, indicating an excellent ion/molecule separation performance.
Downsizing Pt particles and incorporating water dissociation site represents a promising strategy for maximizing atomic utilization efficiency and enhancing catalytic performance in Pt-based hydrogen evolution reaction (HER) electrocatalysts. Here, we present a self-supported Pt/Y(OH) 3 electrocatalyst through a synergistic combination of anion insertion-enhanced electrodeposition and chemical deposition at ambient temperature. The resultant architecture features sub-2 nm Pt nanoclusters (with an average diameter of 1.3 nm) decorated on Y(OH) 3 . The optimized Pt 24 /Y(OH) 3 electrode exhibits impressive HER catalytic performance with an overpotential of 31 mV at 10 mA cm −2 , and maintains stability for 250 h under a high current density of 500 mA cm −2 , surpassing the benchmark Pt/C electrocatalyst. Experimental results and density functional theory (DFT) calculations demonstrate that the sub-2 nm scale of Pt enrich the active sites and the coupled Y(OH) 3 act as a water-dissociation promotor favoring the generation of adsorbed hydrogen on Pt site, thereby boosting the HER activity. Additionally, the strong interaction between Pt nanocluster and Y(OH) 3 stabilizes platinum species from agglomeration, while the robust adhesion of the electrocatalyst to the graphite substrate enhances electron transportation and contributes to superior stability of the catalyst. These results suggest that the innovative self-supported Pt/Y(OH) 3 electrode holds significant promise for practical applications in alkaline hydrogen evolution.
Jiafu Li,Yanran Feng,Xingyun Li,Tianjun Zhang,Xia Liu,Ning Wang,Qiming Sun
Ultrafine metal alloy nanoparticles are emerging as highly effective catalysts for the generation of hydrogen from ammonia borane (AB) hydrolysis. The fabrication of multimetallic alloys with high activity, stability, and metal utilization remains the biggest challenge. Herein, sub-2 nm ternary Rh–Ru–Ni alloys were encapsulated within the interlayers of layer-stripped montmorillonite (MMT) via a simple impregnation method. Experiment and theory results revealed that the synergistic effect of the trimetallic alloy significantly lowers the energy barrier for the AB hydrolysis reaction, by boosting the adsorption and O–H dissociation of H2O molecules. The optimized Rh0.8Ru0.2Ni0.25@MMT-S catalyst achieves high turnover frequency values of 2961 and 784 min–1 at 298 and 273 K, respectively, as well as high recycling stability and thermal resistance. Moreover, the encapsulation method has versatility and can be also applied to synthesize ultrafine Pt- and Ir-based nanoparticles. This study not only highlights the role of the synergistic effect in trimetallic alloys for improving hydrogen evolution but also offers a route to design highly efficient and stable metal nanocatalysts for other applications.
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