The coupled green energy and chemical production by photocatalysis represents a promising sustainable pathway, which poses great challenges for the multifunction integration of catalytic systems. Here we show a promising green photocatalyst design using Cu-ZnIn₂S₄ nanosheets and carbon dots as building units, which enables the integration of reaction, mass transfer, and separation functions in the nano-space, mimicking a nanoreactor. This function integration results in great activity promotion for benzyl alcohol oxidation coupled H₂ production, with H₂/benzaldehyde production rates of 45.95/46.47 mmol g⁻¹ h⁻¹, 36.87 and 36.73 times to pure ZnIn₂S₄, respectively, owning to the enhanced charge accumulation and mass transfer according to in-situ spectroscopies and computational simulations of the built-in electrical field. Near-unity selectivity of benzaldehyde is achieved via the effective separation enabled by the Cu(II)-mediated conformation flipping of the intermediates and subsequent π-π conjugation. This work demonstrates an inspiring proof-of-concept nanoreactor design of photocatalysts for coupled sustainable systems.

Cu₅FeS₄ quantum dots as a single-component photo-assisted electrocatalyst for efficient hydrogen evolution reaction superior to Pt/C.

The electrocatalytic reduction of nitrate to ammonia (NH₃) under mild environmental conditions is attracting increasing attention, in which efficient and inexpensive transition metal catalysts, with the advantages of abundancy and low cost, play a key role. However, synergistic activity and selectivity promotion are still highly challenging. Herein, we developed a hydrogel-assisted strategy to prepare FeNi nanoparticles via the in situ adsorption and reduction of Fe/Ni precursors on a polypyrrole hydrogel. After optimization, the maximum NH₃ yield reached 0.166 mmol h⁻¹ cm⁻², with a Faradaic efficiency of 88.9% and a selectivity of 86.6%. This excellent electrochemical performance was attributed to the mesoporous hydrophilic structure of the polypyrrole hydrogel, which facilitates the homogeneous loading of FeNi nanoparticles and provides a channel for both charge and mass transfer during nitrate reduction, which is important for the conversion of NO₃⁻ to NH₃. Electrochemical active surface area determination and impedance spectroscopy showed that the introduction of hydrogel increased the active sites and improved the charge transfer. This study provides an effective strategy for improving the selectivity and yield of NH₃ in transition metal electrocatalysts by utilizing the three-dimensional hydrogel network and electrical conductivity.

The creation of junctions between 0D and 2D materials can be an efficient strategy to enhance charge separation for solar hydrogen production. In this study, a simple in situ growth method has been used to synthesize a series of 0D/2D Zn-Ag-In-S quantum dots/reduced graphene oxide (ZAIS QDs/RGO) heterojunctions. The developed heterojunctions were characterized for structural characteristics, morphology, and photocatalytic performance, while varying the content of RGO. We observed that photocatalytic hydrogen production reached a maximum at an RGO content of 30 μL (342.34 µmol g⁻¹ h⁻¹), surpassing that of pure ZAIS QDs (110.38 µmol g⁻¹ h⁻¹) by 3.1 times, while maintaining excellent stability. To understand this enhancement, we performed time-resolved fluorescence and electrochemical impedance spectroscopy. The fluorescence lifetime of RGO loaded at 30 μL (417.76 ns) was significantly higher than that of pure ZAIS QDs (294.10 ns) and had the fastest charge transfer, which can be attributed to the charge transfer and storage capacity of RGO to extend the lifetime of photogenerated carriers and improve the charge separation efficiency. This study offers a simple synthesis method for constructing 0D/2D QDs/RGO heterojunction structures and provides a valuable reference for further enhancing the activity and stability of I-III-VI sulfide QDs.