A facile room temperature method to recycle Cd from CdS

Cadmium-based semiconductors have a wide range of applications in light-emitting, energy conversion, photodetection and artificial photosynthesis. With the concern about the potential toxicity of Cd, it is necessary to recycle the element from the Cd based semiconductors. Commonly, the precipitation of Cd cations with S2− is deemed as the end point of recycling. However, actually, CdS is easy to be oxidized and released into the environment and accumulate in the food chain. It still remains challenges on how to refine the Cd element and convert it to the raw material. Herein, we demonstrate a facile room temperature method for recycling Cd from CdS. Cd can be produced from CdS within 3 h with the help of the lithium-ethylenediamine solution. DFT calculations further confirm that the high surface energy of (100) and (101) planes are selectively attacked by the solvated electrons in the solution, which is in good accordance with the XRD, STEM-HAADF and XPS characterizations. With a total recovery efficiency of 88%, Cd is successfully recovered from the CdS powder. This method provides a new perspective on the treatment of Cd-based semiconductor waste, which is of great significance for the recycling of cadmium metal

Morphology-Controlled Synthesis of Au/Cu₂FeSnS₄ Core–Shell Nanostructures for Plasmon-Enhanced Photocatalytic Hydrogen Generation

Copper-based chalcogenides of earth-abundant elements have recently arisen as an alternate material for solar energy conversion. Cu₂FeSnS₄ (CITS), a quaternary chalcogenide that has received relatively little attention, has the potential to be developed into a low-cost and environmentlly friendly material for photovoltaics and photocatalysis. Herein, we report, for the first time, the synthesis, characterization, and growth mechanism of novel Au/CITS core–shell nanostructures with controllable morphology. Precise manipulations in the core–shell dimensions are demonstrated to yield two distinct heterostructures with spherical and multipod gold nanoparticle (NP) cores (Au_sp/CITS and Au_mp/CITS). In photocatalytic hydrogen generation with as-synthesized Au/CITS NPs, the presence of Au cores inside the CITS shell resulted in higher hydrogen generation rates, which can be attributed to the surface plasmon resonance (SPR) effect. The Au_sp/CITS and Au_mp/CITS core–shell NPs enhanced the photocatalytic hydrogen generation by about 125% and 240%, respectively, compared to bare CITS NPs