{'fraction_non_alphanumeric': 0.038621509209744505, 'fraction_numerical': 0.027332144979203804, 'mean_word_length': 5.1911764705882355, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Three-dimensional nickel hydroxide/graphene composite hydrogels and their transformation to NiO/graphene composites for energy storage

Graphene and its functionalized derivatives like graphene oxide (GO) have become handy and convenient building blocks for self-assembly to fabricate graphene-based functional materials with three-dimensional (3D) macroscopic structures. Herein, a convenient one-step hydrothermal method for preparing Ni(OH)2/graphene composite hydrogels (NGHs) with interconnected networks is described. This procedure includes the reduction of GO sheets by hydrazine and the in situ deposition of Ni(OH)2 nanoplates on graphene sheets. Notably, the obtained NGH7.5 (the calculated mass ratio of formed Ni(OH)2 with GO is 7.5 : 1) can offer a high specific capacitance of 1125.4 F g−1 at a charge/discharge rate of 0.5 A g−1, which is almost 2.2 times and 8.1 times higher than Ni(OH)2 and graphene, respectively. Meanwhile, the NGHs also present stable cycling performances with 87.3% capacitance retention after 1000 cycles, which are significantly higher than that of its counterparts of Ni(OH)2. More interestingly, the 3D structure of the NGH can be easily transmitted to NiO/graphene (NiO/G) composites utilizing a facile thermal treatment procedure. The electrode based on the NiO/G composite delivers a discharge capacity of 1349 mA h g−1 and a charge capacity of 992 mA h g−1 at the 1st cycle with a coulombic efficiency of about 73.5%. This work opens a considerable way to fabricate functional graphene-based 3D structures and their composite materials, and makes a significant contribution to energy storage/conversion from alternative energy sources.