Reducing the energy consumption of a hydrogen evolution reaction (HER) at a platinum (Pt) electrode is important for the hydrogen economy. Herein, we report the loading of alpha- or beta-nickel hydroxide (α- or β-Ni­(OH)2) nanostructures on the surface of a Pt electrode to improve its catalytic activity and stability for HER in alkaline electrolytes. Both experimental and theoretical studies reveal that β-Ni­(OH)2 is a better co-catalyst of Pt than α-Ni­(OH)2 for promoting the HER, attributed to the higher water dissociation ability of β-Ni­(OH)2, as well as the stronger interactions between β-Ni­(OH)2 and the Pt electrode. Particularly, the overpotential of the HER in 0.1 M KOH at 10 mA cm–2 is decreased from 278 mV at the Pt electrode to 92 mV at the β-Ni­(OH)2/Pt electrode, and the Tafel slope decreased from 62 to 42 mV dec–1, correspondingly. The performance of the β-Ni­(OH)2/Pt catalytic electrode surpasses that of most of the previously reported electrodes for the same purpose.

A hair-derived carbon/sulfur composite was wrapped with reduced graphene oxide sheets and used as the cathode for lithium–sulfur batteries, exhibiting superior cycling stability, good rate capability and high coulombic efficiency.

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Two dimensional Dion–Jacobson (2D DJ) perovskite has emerged as a potential photovoltaic material because of its unique optoelectronic characteristics. However, due to its low structural flexibility and high formation energy, extra assistance is needed during crystallization. Herein, we study the solvent effect on film formation and trap states of 2D DJ perovskite. It is found that the nucleation process of 2D DJ perovskite can be retarded by extra coordination, which is proved by in situ optical spectra. As a benefit, out-of-plane oriented crystallization and ordered phase distribution are realized. Finally, in 1,5-pentanediammonium (PeDA) based 2D DJ perovskite solar cells (PSCs), one of the highest reported open-circuit voltage (V OC) values of 1.25 V with state-of-the-art efficiency of 18.41% is obtained due to greatly shallowed trap states and suppressed nonradiative recombination. The device also exhibits excellent heat tolerance, which maintains 80% of its initial efficiency after being kept under 85 °C after 3000 h.