Xianli Huang

In situ growth of graphitic carbon nitride films on transparent conducting substrates via a solvothermal route for photoelectrochemical performance

Graphitic carbon nitride (g-C3N4) is a promising metal-free polymeric photocatalyst with a visible light response, but current technologies fail to obtain high quality films for photoelectric devices. Herein, an efficient solvothermal strategy has been developed to prepare continuous and complete graphitic carbon nitride films. The resulting films exhibit a remarkable enhancement in photoelectrochemical performance, much superior to the thermal condensation g-C3N4 films. This is attributed to the red-shift of visible light absorption and the improvement of charge separation and transport. Importantly, the general, efficient and one-step wet-chemical strategy opens up new possibilities for carbon nitride in photoelectric devices based on renewable solar energy applications.

Synthesis of yellow mesoporous Ni-doped TiO2 with enhanced photoelectrochemical performance under visible light

A novel ordered mesoporous Ni-doped TiO2 was successfully prepared via an in situ sol–gel method. TEM and SEM images showed that the synthesized material had a highly ordered and uniform mesoporous structure. EDS and XPS confirmed that the nickel element was doped into the TiO2 crystal lattice homogeneously in the form of Ni2+ ions. Meanwhile, the doping of Ni changed the positions of the energy bands of TiO2, resulting in the decrease of the band gap, and enhanced the absorption of visible light. Moreover, due to the defect sites induced by doping which could cause recombination of electrons and holes, different doping amounts were investigated in order to achieve optimized parameters. As a result, when the molar ratio of Ni/Ti was 0.01, the ordered mesoporous Ni-doped TiO2 exhibited the highest photocurrent density of 3.1 μA cm−2 at 1.3 V (vs. RHE) under visible light irradiation.

Constructing Ordered Three-Dimensional TiO2 Channels for Enhanced Visible-Light Photocatalytic Performance in CO2 Conversion Induced by Au Nanoparticles

As a typical photocatalyst for CO2 reduction, practical applications of TiO2 still suffer from low photocatalytic efficiency and limited visible-light absorption. Herein, a novel Au-nanoparticle (NP)-decorated ordered mesoporous TiO2 (OMT) composite (OMT-Au) was successfully fabricated, in which Au NPs were uniformly dispersed on the OMT. Due to the surface plasmon resonance (SPR) effect derived from the excited Au NPs, the TiO2 shows high photocatalytic performance for CO2 reduction under visible light. The ordered mesoporous TiO2 exhibits superior material and structure, with a high surface area that offers more catalytically active sites. More importantly, the three-dimensional transport channels ensure the smooth flow of gas molecules, highly efficient CO2 adsorption, and the fast and steady transmission of hot electrons excited from the Au NPs, which lead to a further improvement in the photocatalytic performance. These results highlight the possibility of improving the photocatalysis for CO2 reduction under visible light by constructing OMT-based Au-SPR-induced photocatalysts.

Fabrication of perovskite-based porous nanotubes as efficient bifunctional catalyst and application in hybrid lithium–oxygen batteries

The design of efficient oxygen electrocatalysts is extremely important and urgent for much energy storage and conversion equipment. Among these, the high energy densities of lithium–oxygen batteries (LOBs) have driven us to explore bifunctional catalysts. Compared with non-aqueous LOBs, which have been blamed for poor cycling stability due to their undesirable side reaction, hybrid LOBs have been considered an alternative solution due to their high electrochemical reversibility and safeness. Here, one-dimensional hierarchical mesoporous/macroporous LaMn0.7Co0.3O3−x nanotubes were synthesized through an electrospinning method combined with an annealing treatment. With the suitable heat treatment and rational doping with elemental Co, the LMCO-800 sample shows a well-designed hierarchical porous nanotube structure and possess great bifunctional electrocatalytic performance. The linear sweep voltammetry (LSV) curves show that the half-wave potential (E1/2) of the LMCO-800 sample is 0.72 V (vs. RHE) and the average electron transfer number (n) is calculated to be 3.8. Moreover, the successful doping of elemental Co into the LMCO-800 nanotubes can shorten the average distance of the Mn–Mn atoms and promote the formation of O–O bonds, contributing to the enhanced OER performance. The high specific surface area and one-dimensional nanotubes can greatly benefit oxygen diffusion, facilitate electrolyte infiltration and improve electron transfer. Consequently, the as-assembled hybrid lithium–oxygen batteries with an LMCO-800 cathode exhibit superior cycling stability.