A simple one-step calcination route was used to prepare Ti(3+) self-doped TiO2/g-C3N4 heterojunctions by mixture of H2Ti3O7 and melamine. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-vis DRS) technologies were used to characterize the structure, crystallinity, morphology, and chemical state of the as-prepared samples. The absorption of the prepared Ti(3+) self-doped TiO2/g-C3N4 heterojunctions shifted to a longer wavelength region in comparison with pristine TiO2 and g-C3N4. The photocatalytic activities of the heterojunctions were studied by degrading methylene blue under a 30 W visible-light-emitting diode irradiation source. The visible-light photocatalytic activities enhanced by the prepared Ti(3+) self-doped TiO2/g-C3N4 heterojunctions were observed and proved to be better than that of pure TiO2 and g-C3N4. The photocatalysis mechanism was investigated and discussed. The intensive separation efficiency of photogenerated electron-hole in the prepared heterojunction was confirmed by photoluminescence (PL) spectra. The removal rate constant reached 0.038 min(-1) for the 22.3 wt % Ti(3+) self-doped TiO2/g-C3N4 heterojunction, which was 26.76 and 7.6 times higher than that of pure TiO2 and g-C3N4, respectively. The established heterojunction between the interfaces of TiO2 nanoparticles and g-C3N4 nanosheets as well as introduced Ti(3+) led to the rapid electron transfer rate and improved photoinduced electron-hole pair's separation efficiency, resulting in the improved photocatalytic performance of the Ti(3+) self-doped TiO2/g-C3N4 heterojunctions.

With the increasing energy demand together with the deteriorating environment and decreasing fossil fuel resources, the development of highly efficient energy conversion and storage devices is one of the key challenges of both fundamental and applied research in energy technology. Melamine sponges (MS) with low density, high nitrogen content, and high porosity have been used to design and obtain three‐dimensional porous carbon electrode materials. More importantly, they are inexpensive, environment‐friendly, and easy to synthesize. There have been many reports on the modification of carbonized MS and MS‐based composites for supercapacitor and lithium battery electrode materials. In this paper, recent studies on the fabrication of electrode materials using MS as raw materials have been mainly reviewed, including carbonation, doping activation, and composite modification of MS, and expectations for the development of porous carbon materials for energy storage as a reference with excellent performance, environment‐friendliness, and long life.

Direct Z-scheme NiTiO/g-CN heterojunctions were successfully assembled by using simple calcination method and the photoelectrochemical and photocatalytic performance were investigated by light emitting diode (LED). The photoanode composed by the heterojunction with about 50 wt % NiTiO content exhibits the best photoelectrochemical activity with photoconversion efficiency up to 0.066%, which is 4.4 and 3.13 times larger than NiTiO or g-CN. The remarkably enhanced photoelectrochemical and photocatalytic activity of the heterojunction can be due to the efficiently photogenerated electron-hole separation by a Z-scheme mechanism.

Solar steam generation and adsorption, as promising technologies to tackle water pollution, have gained increasing research interest in recent years. In this paper, 3D spherical carbonized platanus fruit with special surface topology and inner interconnected porous structure is used as a superior solar evaporator and an adsorbent for dye removal with easy separation from treated water. The dual‐functional material with single component is prepared by a simply carbonizing biowaste platanus fruit. A high evaporation rate up to 2.00 kg m−2 h−1 under one sun is achieved by 3D spherical evaporator. 3D evaporator also presents outstanding water evaporation under low light intensity, angle‐independent water evaporation, and long‐term cycling stability. Importantly, high‐capacity dye adsorption and generation of purified water are simultaneously achieved with the assistance of solar‐driven evaporation under one sun. Thus, the monolithic, dual‐functional 3D material with a simple preparation process, low cost, mechanical robustness, and environmental friendliness has great potential for solar steam generation and solar water evaporation‐assisted adsorption. This study proposes a simple route to design 3D solar evaporators with surface topology and innovatively provides a high‐efficiency method for tackling water pollution.

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