Enhanced photocatalytic hydrogen evolution over 0D/3D NiTiO3 nanoparticles/CdIn2S4 microspheres heterostructure photocatalyst

Constructing S-scheme heterojunction is regarded as an effective mode to motivate excellent photocatalytic performance for hydrogen generation. This paper prepares NiTiO₃/CdIn₂S₄ S-scheme heterostructure photocatalyst by hydrothermal method successfully. In the experiments, 20 wt% NiTiO₃/CdIn₂S₄ has the supreme photocatalytic activity with the H₂ generation rate of 5168.6 μmol g⁻¹ h⁻¹ and the apparent quantum yield (AQY) of 5.14% at 420 nm, approximately 7.7 times of pure CdIn₂S₄. Through the phase characterization analyses, NiTiO₃ and CdIn₂S₄ successfully compounded, with NiTiO₃ nanoparticles wrapping around CdIn₂S₄ microspheres to form the irregular clumps. Further analyses of performance reveal the larger specific surface area, wider absorption region, faster charge transfer rate, outstanding photostability and recyclability for 20 wt% NiTiO₃/CdIn₂S₄, all of which play the significant role in photocatalytic hydrogen evolution activity. Finally, a plausible S-scheme photocatalytic mechanism for NiTiO₃/CdIn₂S₄ is proposed. This study provides a novel and effective S-scheme photocatalyst for hydrogen generation from water splitting.     

Facile construction of porous C-PDA@CN-ms core-shell heterostructures with superior photocatalytic H2 evolution

Building carbon nitride (CN)-based core shell heterostructures is an effective strategy to enhance the photocatalytic performance and stability by optimize the interface area and protect the CN core, respectively. Moreover, by fabricating the porous structures in core shells can further optimize the light absorption, charge separation, and mass transfer. Herein, we have constructed porous C-PDA–CN–ms core-shell heterostructures through a facile green molten salt (ms) sculpture the polydopamine (PDA) derived carbon (C-PDA) shells with CN core. In which, the C-PDA-CN core-shells arise from in situ polymerization of dopamine (DA) on the surface of melamine to form PDA@melamine coatings followed by thermal polycondensation. The molten salts at high-temperature act as a green fluid immersing in and out of C-PDA-CN core-shells to further produce porous structures. The 1 wt% C-PDA–CN–ms with porous core-shell structures display photocatalytic H₂ evolution rate of 3830 μmol h⁻¹ g⁻¹, which is 20.8 times enhancement of 1 wt% C-PDA-CN core-shells, even 73.6 times higher than that of pristine CN. It reveals that the porous and core-shell heterostructures endow C-PDA–CN–ms enhanced light absorption, various charge transport channels for improved charge carrier separation and transfer, contributing to the superior photocatalytic H₂ evolution performance. Our work opens a new window for the green construction of porous core-shell heterostructures of CN-based photocatalysts.     

Origin mechanism of pitting corrosion induced by cerium inclusions

In this paper, the origin mechanism of pitting corrosion induced by Ce₂O₃, Ce₂O₂S, and CeAlO₃ inclusions in a microalloyed steel was investigated by field emission scanning electron microscopy with energy dispersive spectroscopy and electron backscattered diffraction, conductivity atomic force microscopy, immersion test, and first-principles calculation. The results show that the Ce₂O₃, Ce₂O₂S, and CeAlO₃ inclusions are non-conductive, which are impossible to form corrosion couples with the steel matrix. There are no obvious lattice distortion zones in the steel matrix around the Ce₂O₃, Ce₂O₂S, and CeAlO₃ inclusions, so it is difficult to form micro-galvanic corrosion near the Ce inclusion. The order of work functions of the Ce inclusions and the steel matrix from small to large is Ce₂O₂S < Ce₂O₃<CeAlO₃<steel matrix, which is consistent with their dissolution sequence in the immersion test in 3.5 wt% NaCl solution. Consequently, it is effective and reliable to use work function to predict or judge the dissolution behaviors of the Ce inclusions or steel matrix in corrosive solution. The Ce₂O₃, Ce₂O₂S, and CeAlO₃ inclusions have the tendency of self-dissolution and dissolve preferentially to the steel matrix in the solution by the salt effect, which lead to pitting corrosion of Ce-containing microalloyed steel.     

Electrochemical study on the effect of hydrogen on the passive film of selective laser melted 316L stainless steel in a proton exchange membrane water electrolyzer environment

The effect of hydrogen on the passivation behavior and electrochemical characteristics of selective laser melted (SLMed) 316L stainless steel in a simulated anode environment for a proton exchange membrane water electrolyzer (PEMWE) was studied. The results indicate that hydrogen charged into the sample increased the ratio of superficial Fe²⁺/Fe³⁺ and OH⁻/O²⁻, increased the concentration of point defects, reduced the film thickness, and weakened its protective effect. The film near 0.6 V_SCE showed n-type semiconductor behavior. Hydrogen charging resulted in a higher defect density and thinner space charge layer in the film, which promoted the invasion of aggressive ions.