Hierarchical NiO@N‐Doped Carbon Microspheres with Ultrathin Nanosheet Subunits as Excellent Photocatalysts for Hydrogen Evolution

Abstract

Achieving highly efficient hierarchical photocatalysts for hydrogen evolution is always challenging. Herein, hierarchical mesoporous NiO@N‐doped carbon microspheres (HNINC) are successfully fabricated with ultrathin nanosheet subunits as high‐performance photocatalysts for hydrogen evolution. The unique architecture of N‐doped carbon layers and hierarchical mesoporous structures from HNINC could effectively facilitate the separation and transfer of photo‐induced electron–hole pairs and afford rich active sites for photocatalytic reactions, leading to a significantly higher H2 production rate than NiO deposited with platinum. Density functional theory calculations reveal that the migration path of the photo‐generated electron transfer is from Ni 3d and O 2p hybrid states of NiO to the C 2p state of graphite, while the photo‐generated holes locate at Ni 4s and Ni 4p hybrid states of NiO, which is beneficial to improve the separation of photo‐generated electron–hole pairs. Gibbs free energy of the intermediate state for hydrogen evolution reaction is calculated to provide a fundamental understanding of the high H2 production rate of HNINC. This research sheds light on developing novel photocatalysts for efficient hydrogen evolution.

Ultrathin 2D Metal–Organic Framework Nanosheets In situ Interpenetrated by Functional CNTs for Hybrid Energy Storage Device

“…Particularly, confining the thickness of intrinsically non-layered structure into nanoscale and keeping a large lateral dimension are likely to change their inter-particle connectivity [12,35]. For ultrathin nanosheets, moreover, the active sites can be sufficiently exposed, which is capable of tuning the band gap energy and the density of states near the Fermi level, thus enhancing electrical conductivity [36][37][38][39]. The exposed metal active sites could serve as highly active centers to decrease the energy barrier of faradaic redox reactions and to facilitate the capture ability of electrolyte ions, which is conducive to improve the electrochemical reaction kinetics [35,38,40].…”

In Situ Growth of Ultrathin NiO Nanosheet‐Arrays on MOF‐Derived Porous Co3O4 Scaffolds as High‐Performance Cathode for Asymmetric Supercapacitors

“…The high‐resolution XPS spectrum of O 1s in Figure 2f is deconvoluted into three distinct peaks. The peak located at 529.5 eV corresponds to the typical lattice oxygen (O L ), whereas the peaks at 531.3 and 532.8 eV can correspond to the oxygen‐deficient region (O V ) and dissociated and chemisorbed oxygen (O C ), respectively [18a] . Significantly, the oxygen vacancies can enhance the surface charge storage as well as the cation redox reaction [18b]…”

Modulating the electronic structure of nanomaterials to enhance polysulfides confinement for advanced lithium–sulfur batteries

“…[15][16][17][18] Furthermore, heteroatoms (i.e., B, N, P, S) are introduced into the surface of carbon materials, which can produce strong chemical affinity, and then suppress the diffusion of LiPSs more efficiently. [19][20][21] In addition, due to the high activation energy, the conversion from soluble LiPSs to insoluble Li 2 S 2 /Li 2 S in electrode/electrolyte interface is sluggish, which will aggravate the diffusion of LiPSs from cathode to anode. 22,23 Hence, accelerating the sulfur redox reaction has recently emerged as a new frontier of research, and many catalysts, such as transition-metal oxides, suldes, nitrides, were employed as sulfur hosts in Li-S batteries.…”