A green and scalable route is developed to prepare hierarchical porous carbon sheets (HPCS) from biomass (cornstalk) directly under an air atmosphere instead of inert gas protection. In addition, the method adopts non-toxic NaCl and KCl mixed salt as reaction media to regulate the activation process, which avoids the corrosive and poisonous KOH and ZnCl₂ reagents. Meanwhile, the porous structures of HPCS can be well-manipulated by the salt templates and the etching effects of the oxygen atom as well as the high energy molten salt media. The as-obtained HPCS consist of an ultra-thin sheet structure (∼4.6 nm in thickness) and abundant hierarchical pores, which facilitates electrolyte diffusion and ion transfer. In addition, the high specific surface area of 1588 m² g⁻¹ provides sufficient active sites and the rich O doping introduces pseudocapacitance. Therefore, the as-prepared HPCS exhibit a high specific capacitance of 407 F g⁻¹ at 1 A g⁻¹ in a three-electrode system. Moreover, the assembled symmetric supercapacitor in a two-electrode system also exhibits an outstanding specific capacitance of 413 F g⁻¹ at 0.5 A g⁻¹, an excellent rate capacity and a long-term cycling stability with 92.6% of initial capacitance retention after 20 000 cycles at 5 A g⁻¹, which are comparable to those of the porous carbons activated with traditional methods. It is expected that this green and facile technique could serve as an effective and scalable method to prepare optimized HPCS with tunable porous structures from biomass for electrochemical energy storage applications.

Hierarchical ZnO composed of ultrathin nanosheets as secondary structures were fabricated through a hydrothermal method. Afterwards, hexagonal wurtzite CdS with diameter between 50–100 nm were incorporated on the wurtzite ZnO sheets with the assistance of ultrasonic irradiation. The hybrid ZnO/CdS samples were intensively investigated by SEM, TEM, HRTEM, XRD, XPS, PL and the UV-Vis absorption spectrum. The photocatalytic trials confirmed that the ZnO/CdS hierarchical heterostructures exhibit improved degradation efficiency compared to pure ZnO sample under natural sunlight. CdS nanoparticles are believed to serve as photo-sensitizers to extend the absorption spectrum to the visible region and the loading amount was also found to play a crucial role in influencing the degradation efficiency. Moreover, the photodegradation kinetics of RhB via using CdS/ZnO as photocatalysts were also systematically discussed. Finally, a mechanism based on this band-gap alignment was proposed to elucidate the efficiency enhancement of the hybrid photocatalysts.

Monodisperse TiO₂ hollow spheres assembled by nanospindles were prepared via the facile hydrothermal reaction of peroxotitanium complex precursors. Time dependent trails revealed that the shape evolution involved a one-step chemical conversion from amorphous Ti complex microspheres to anatase TiO₂ hierarchical hollow spheres. Meanwhile, the sizes of the spheres could be tuned in a region of 400–1000 nm by simply adjusting the ammonia dosage of the precursor solution. Furthermore, these as-prepared hollow spheres were deposited as a scattering layer on top of the TiO₂ nanocrystalline film, and a high energy conversion efficiency of 8.10% was demonstrated based on the bilayer photoanode, in contrast to a 7.29% conversion efficiency for the cell with a pure nanocrystalline photoanode.

Mesocrystalline Cu₂O hollow nanocubes (MCHNs) were successfully prepared by a facile reduction reaction under room temperature. CuCl₂ played a dual role as both copper source and morphology controlling reagent for the oriented aggregation of primary Cu₂O crystallites toward MCHNs. Due to the high crystallinity and high specific surface area, the as-prepared MCHNs exhibited high electrocatalytic activity for the reduction of hydrogen peroxide (H₂O₂) and oxidation of glucose. The non-enzymatic amperometric biosensors based on the MCHNs demonstrated a detection limit of 1.03 μM and a sensitivity of 156.6 μA mM⁻¹ for H₂O₂, as well as a detection limit of 0.87 μM and sensitivity of 52.5 μA mM⁻¹ for glucose. The high sensitivities and anti-interference ability made the MCHNs a promising material in non-enzymatic biosensors.