As a cost-effective and environmentally friendly secondary energy source, hydrogen energy is one of the top future targets for the development of clean energy. The electrolysis of water to produce...

No abstract

Developing highly efficient and stable electrocatalysts is the key to realize hydrogen production from industrial electrolytic water. In this study, we constructed Co(OH) 2 and CoP ultrathin nanosheet arrays on titanium mesh using electrodeposition and phosphating processes. In alkaline conditions, the Co(OH) 2 /Ti-2.0 needed overpotentials of 414 and 457 mV to achieve 500 and 1000 mA cm −2 for oxygen evolution reaction. Mechanism research showed that CoOOH formed by preoxidation of Co(OH) 2 was the actual active substance. After low-temperature phosphorization of Co(OH) 2 , CoP nanosheets generated abundant defects and increased reactive sites, and CoP/ Ti-2.0 exhibited high activity in the all-pH hydrogen evolution reaction (overpotentials of 106, 116, and 131 mV in acidic, alkaline, and neutral solutions at 10 mA cm −2 , respectively). Density functional theory calculations showed the free energy of hydrogen adsorption of CoP. As efficient electrode materials, the Co(OH) 2 and CoP ultrathin nanosheet arrays on Ti mesh can be assembled to an alkaline electrolyzer, which required only 1.530 V to drive 50 mA cm −2 for overall water splitting with strong durability.

MoX 2 (X = O, S) layered structures are promising anode materials for lithium-ion batteries because of their intrinsically high theoretical capacity. Yet, the poor electrical conductivity and substantial volume change during reaction with Li + ions greatly limit their practical application. This can be mitigated by developing a proper carbon framework for effective confinement of the growth of active materials. Herein, a universal carbon framework template has been exploited for the synthesis of thin MoX 2 nanosheets encapsulated in mesoporous hollow carbon frameworks (MHCFs) by the confinement approach, forming a MoX 2 /C interconnected network. The porous hierarchical architectures offer sufficient void space for MoX 2 nanosheets during the expansion process. Meanwhile, the confining effect of hollow carbon spheres can prevent aggregation and spreading out from the carbon of MoX 2 nanosheets to guarantee high structural integrity upon cycling (638 mA h g −1 for MoO 2 /C at 1 A g −1 after the 1000th cycle and 525 mA h g −1 for MoS 2 /C after 200 at 1 A g −1 ).