Flower-like phosphorus-doped g-C3N4 with a high surface area was synthesized using cyanuric acid–melamine supramolecular precursors which were absorbed by phosphoric acid.

Semiconductor nanostructures have received considerable attention in the field of photocatalytic hydrogen evolution. However, eco-friendly, high efficiency, and low-cost semiconductor materials are still desired. In consideration of this, herein, we design a new and economic noble-metal-free CdS/ZnCoO (CdS/ZCO) nanohybrid photocatalyst using a metal-organic framework (MOF) template, which is a framework structure composed of organic ligands and metal ion nodes with different numbers of connections. The as-prepared CdS/ZCO composites with a large specific surface area and porous hollow structure exhibit remarkable catalytic activity and high stability for hydrogen generation. The hydrogen evolution rate is about 3978.6 μmol g h with lactic acid as the sacrificial agent when the optimized amount of CdS nanoparticles (30 wt%) is decorated on the ZCO frame, and the production efficiency of H for CdS/ZCO is 4 times higher than that for CdS nanospheres or CdS/CoO. The significantly enhanced photocatalytic activity of CdS/ZCO is attributed to the efficient charge separation and transfer between the phase boundary of CdS and ZCO. In addition, the composites exhibit better hydrogen production in lactic acid than in methanol, and the remarkable catalytic activity and high stability of the CdS/ZCO composites for hydrogen evolution indicate that MOF-based composite materials have potential application prospects in energy conversion.

Controlled synthesis of porous metal oxides with desired morphology has been motivating scientists to explore and develop new preparation methodologies. Among them, thermal decomposition of metal-organic frameworks (MOFs) has been employed for the fabrication of several metal oxides. In this work, this strategy is employed to prepare mesoporous and tetragonal zirconia (t-ZrO2) from metal-organic framework (UiO-66), acting as both morphological template and zirconium source. This process avoids the use and removal of extra template as well as the addition of stabilizers for t-ZrO2. After thermal decomposition at 500 °C, t-ZrO2 inherited octahedral morphology from the pristine precursor, and possessed small nanoparticles with an average size of 3.1 nm. The derived t-ZrO2 had a large surface area of 174 m 2 /g and the pore diameter of 5-8 nm. The formation mechanism of t-ZrO2 was also discussed. This simple and potentially universal strategy can be used to fabricate porous metal oxides with desired shape for many applications.

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The halogen elements modification strategy of TiO encounters a bottleneck in visible-light H production. Herein, we have for the first time reported a hierarchical honeycomb Br-, N-codoped anatase TiO catalyst (HM-Br,N/TiO) with enhanced visible-light photocatalytic H production. During the synthesizing process, large amounts of meso-macroporous channels and TiO nanosheets were fabricated in massive TiO automatically, constructing the hierarchical honeycomb structure with large specific surface area (464 m g). cetyl trimethylammonium bromide and melamine played a key role in constructing the meso-macroporous channels. Additionally, HM-Br,N/TiO showed a high visible-light H production rate of 2247 μmol h g, which is far more higher than single Br- or N-doped TiO (0 or 63 μmol h g, respectively), thereby demonstrating the excellent synergistic effects of Br and N elements in H evolution. In HM-Br,N/TiO catalytic system, the codoped Br-N atoms could reduce the band gap of TiO to 2.88 eV and the holes on acceptor levels (N acceptor) can passivate the electrons on donor levels (Br donor), thereby preventing charge carriers recombination significantly. Furthermore, the proposed HM-Br,N/TiO fabrication strategy had a wide range of choices for N source (e.g., melamine, urea, and dicyandiamide) and it can be applied to other TiO materials (e.g., P25) as well, thereby implying its great potential application in visible-light H production. Finally, on the basis of experimental results, a possible photocatalytic H production mechanism for HM-Br,N/TiO was proposed.