Carbon hollow spheres as cocatalyst of Cu-doped TiO_(2)nanoparticles for improved photocatalytic H_(2)generation

The reasonable employment of cocatalyst in photocatalysis can effectively promote the photocatalytic H_(2)production activity.In this study,carbon hollow spheres(C),as a good conductive nonmetallic material,have been utilized as a novel cocatalyst and a matrix for loading the Cu-doped-TiO_(2)nanoparticles by a successive hydrother-mal method and metal molten salt method.The Cu-doped-TiO_(2)nanoparticles were tightly anchored on the surface of carbon hollow sphere to form a zero-dimensional/three dimensional(0D/3D)Cu-doped-TiO2/C heterojunction.The optimal Cu-doped-TiO_(2)/C heterojunction demon-strated greatly enhanced photocatalytic H_(2) generation activity(14.4 mmol·g^(-1)·h^(-1))compared with TiO_(2)(0.33 mmol·g^(-1)·h^(-1))and TiO_(2)/C(0.7 mmol·g^(-1)·h^(-1)).The performance improvement was mainly due to the syner-gistic effect of carbon hollow sphere cocatalyst and Cu-doping,the Cu-doping in TiO_(2)nanoparticles can minimize charge recombination and enhance the available photoex-cited electrons,while the 3D carbon hollow spheres can act as electron traps to accelerate the charge separation and offer abundant active sites for solar water splitting reaction.

Three-dimensional hierarchically porous nitrogen-doped carbon from water hyacinth as selenium host for high-performance lithium-selenium batteries

Hierarchically porous nitrogen-doped carbon(HPNC) with interconnected micro-,meso-,and macropores was generated from KOH and urea etching as a carbon scaffold to infuse Se.In this structure,micropores confine Se as single-chain molecules,preventing the generation of higher-order polyselenides,the mesopores provide effective pathways for electrolyte diffusion and ion transport and offer sufficient void space to accommodate the volume change of Se upon lithiation/delithiation,and the doped nitrogen improves the electrical conductivity of HPNC and increases the utilization of Se.When applied as a scaffold for Se in a lithium-selenium battery,the Se/HPNC cathode with a large Se content of 67.6 wt% maintains a high discharge capacity of 410 mAh·g^(-1) at the 500 th cycle at1.0 C,and it demonstrates a discharge capacity as high as371 mAh·g^(-1) even at a high current density of 5.0 C.Moreover,when the current density returns to 0.2 C,the discharge capacity recovers to 527 mAh·g^(-1) with a capacity retention rate of 90.5% for the first 0.2 C,indicating the excellent structural stability of HPNC.HPNC has significant potential for application in energy storage systems.