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Hydrogen production is vital for meeting future energy demands and managing environmental sustainability. Electrolysis of water is considered as the suitable method for H2 generation in a carbon‐free pathway. Herein, the synthesis of highly efficient Co9S8‐Ni3S2 based hierarchical nanoflower arrays on nickel foam (NF) is explored through the one‐pot hydrothermal method (Co9S8‐Ni3S2/NF) for overall water splitting applications. The nanoflower arrays are self‐supported on the NF without any binder, possessing the required porosity and structural characteristics. The obtained Co9S8‐Ni3S2/NF displays high hydrogen evolution reaction (HER), as well as oxygen evolution reaction (OER), activities in 1 m KOH solution. The overpotentials exhibited by this system at 25 mA cm−2 are nearly 277 and 102 mV for HER and OER, respectively, in 1 m KOH solution. Subsequently, the overall water splitting was performed in 1 m KOH solution by employing Co9S8‐Ni3S2/NF as both the anode and cathode, where the system required only 1.49, 1.60, and 1.69 V to deliver the current densities of 10, 25, and 50 mA cm−2, respectively. Comparison of the activity of Co9S8‐Ni3S2/NF with the state‐of‐the‐art Pt/C and RuO2 coated on NF displays an enhanced performance for Co9S8‐Ni3S2/NF both in the half‐cell as well as in the full cell, emphasizing the significance of the present work. The post analysis of the material after water electrolysis confirms that the surface Co(OH)2 formed during the course of the reaction serves as the favorable active sites. Overall, the activity modulation achieved in the present case is attributed to the presence of the open‐pore morphology of the as formed nanoflowers of Co9S8‐Ni3S2 on NF and the simultaneous presence of the surface Co(OH)2 along with the highly conducting Co9S8‐Ni3S2 core, which facilitates the adsorption of the reactants and subsequently its conversion into the gaseous products during water electrolysis. [ABSTRACT FROM AUTHOR]

The yielding behavior of dense thermosensitive microgel suspensions of poly(N‐isopropylacrylamide) with two different particle morphologies viz core–shell (CS) morphology and particles with uniform crosslink density were studied. Structural properties were examined using dynamic light scattering and yielding behavior was investigated by nonlinear oscillatory rheology. Suspensions of particles with uniform crosslinking density showed a typical hard sphere like behavior with the loss modulus (G″) exhibiting a single peak due to cage breaking while CS type particles shows a double yielding at different ranges of strain similar to that seen in attractive colloidal glasses. The first yielding process in CS microgels is interpreted as due to the disentanglement of the overlapped polymer chains from the shells of the neighboring microgels and the second yielding process due to the breakage of cages formed by neighboring microgel particles. Current study suggests that the interpenetration of polymer chains at high concentrations sets in an attractive like potential leading to double yielding phenomena in an otherwise purely repulsive system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48625. [ABSTRACT FROM AUTHOR]

Hydrogen production is vital for meeting future energy demands and managing environmental sustainability. Electrolysis of water is considered as the suitable method for H 2 generation in a carbon-free pathway. Herein, the synthesis of highly efficient Co 9 S 8 -Ni 3 S 2 based hierarchical nanoflower arrays on nickel foam (NF) is explored through the one-pot hydrothermal method (Co 9 S 8 -Ni 3 S 2 /NF) for overall water splitting applications. The nanoflower arrays are self-supported on the NF without any binder, possessing the required porosity and structural characteristics. The obtained Co 9 S 8 -Ni 3 S 2 /NF displays high hydrogen evolution reaction (HER), as well as oxygen evolution reaction (OER), activities in 1 m KOH solution. The overpotentials exhibited by this system at 25 mA cm -2 are nearly 277 and 102 mV for HER and OER, respectively, in 1 m KOH solution. Subsequently, the overall water splitting was performed in 1 m KOH solution by employing Co 9 S 8 -Ni 3 S 2 /NF as both the anode and cathode, where the system required only 1.49, 1.60, and 1.69 V to deliver the current densities of 10, 25, and 50 mA cm -2 , respectively. Comparison of the activity of Co 9 S 8 -Ni 3 S 2 /NF with the state-of-the-art Pt/C and RuO 2 coated on NF displays an enhanced performance for Co 9 S 8 -Ni 3 S 2 /NF both in the half-cell as well as in the full cell, emphasizing the significance of the present work. The post analysis of the material after water electrolysis confirms that the surface Co(OH) 2 formed during the course of the reaction serves as the favorable active sites. Overall, the activity modulation achieved in the present case is attributed to the presence of the open-pore morphology of the as formed nanoflowers of Co 9 S 8 -Ni 3 S 2 on NF and the simultaneous presence of the surface Co(OH) 2 along with the highly conducting Co 9 S 8 -Ni 3 S 2 core, which facilitates the adsorption of the reactants and subsequently its conversion into the gaseous products during water electrolysis., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)