Hydrothermally synthesized highly dispersed Na2Ti3O7 nanotubes and their photocatalytic degradation and H2 evolution activity under UV and simulated solar light irradiation

Multilayer Strategy for Photoelectrochemical Hydrogen Generation: New Electrode Architecture that Alleviates Multiple Bottlenecks

Years of research have demonstrated that the use of multiple components is essential to the development of a commercial photoelectrode to address specific bottlenecks, such as low charge separation and injection efficiency, low carrier diffusion length and lifetime, and poor durability. A facile strategy for the synthesis of multilayered photoanodes from atomic-layer-deposited ultrathin films has enabled a new type of electrode architecture with a total multilayer thickness of 15-17 nm. We illustrate the advantages of this electrode architecture by using nanolayers to address different bottlenecks, thus producing a multilayer photoelectrode with improved interface kinetics and shorter electron transport path, as determined by interface analyses. The photocurrent density was twice that of the bare structure and reached a maximum of 33.3 ± 2.1 mA cm^-2 at 1.23 V_RHE. An integrated overall water-splitting cell consisting of an electrocatalytic NiS cathode and Bi₂S₃/NiS/NiFeO/TiO₂ photoanode was used for precious-metal-free seawater splitting at a cell voltage of 1.23 V without degradation. The results and root analyses suggest that the distinctive advantages of the electrode architecture, which are superior to those of bulk bottom-up core-shell and hierarchical architectures, originate from the high density of active sites and nanometer-scale layer thickness, which enhance the suitability for interface-oriented energy conversion processes.

In situ growth of MnO@Na2Ti6O13 heterojunction nanowires for high performance supercapacitors

One-dimensional tunnel and layer frame crystal structure materials are extremely attractive for energy storage in electrode materials. The energy storage properties of the electrode materials depend on their conductivity. Furthermore, the conductivity of electrode materials can be tailored through combination or doping with other materials, which transforms their properties from semiconductor to semimetallic or metallic and allow them to show unequaled performance for storage devices. In this work, heterostructures of manganese oxide (MnO) and modified sodium titanate (Na₂Ti₆O₁₃) (MnO@Na₂Ti₆O₁₃) nanowires are attained by the in situ thermal decomposition method. The heterojunction between MnO and Na₂Ti₆O₁₃ allows the semiconductor properties of pure Na₂Ti₆O₁₃ to show remarkable metallic behavior for improving the electrochemical performance. The capacitance of MnO@Na₂Ti₆O₁₃ heterojunction nanowires can reach 272.3 F g^-1, a power intensity of 250 W kg^-1 at the energy density of 37.83 Wh kg^-1 and retain 5000 W kg^-1 at 6.67 Wh kg^-1 as well. The energy storage mechanism of the MnO@Na₂Ti₆O₁₃ heterostructure is studied by density functional theory. All of the results show that the MnO@Na₂Ti₆O₁₃ heterostructure material has the potential to be an excellent supercapacitor material in the future.