Hematite photoanode modified with inexpensive hole-storage layer for highly efficient solar water oxidation

In Situ Synthesis of Ti:Fe2O3/Cu2O p-n Junction for Highly Efficient Photogenerated Carriers Separation

High photoelectrochemical water oxidation efficiency can be achieved through an efficient photogenerated holes transfer pathway. Constructing a photoanode semiconductor heterojunction with close interface contact is an effective tactic to improve the efficiency of photogenerated carrier separation. Here, we reported a novel photoanode p-n junction of Ti:Fe2O3/Cu2O (n-Ti:Fe2O3 and p-Cu2O), Cu2O being obtained by in situ reduction in CuAl-LDH (layered double hydroxides). The Ti:Fe2O3/Cu2O photoanode exhibits a high photocurrent density reaching 1.35 mA/cm2 at 1.23 V vs. RHE is about 1.67 and 50 times higher than the Ti:Fe2O3 and α-Fe2O3 photoanode, respectively. The enhanced PEC activity for the n-Ti:Fe2O3/p-Cu2O photoelectrode is due to the remarkable surface charge separation efficiency (ηsurface 85%) and bulk charge separation efficiency (ηbulk 72%) formed by the p-n junction and the tight interface contact formed by in situ reduction. Moreover, as a cocatalyst, CuAl-LDH can protect the Ti:Fe2O3/Cu2O photoanode and improve its stability to a certain extent. This study provides insight into the manufacturing potential of in situ reduction layered double hydroxides semiconductor for designing highly active photoanodes in the field of photoelectrochemical water oxidation.

NIR-II driven photocatalytic hydrogen peroxide-supply on metallic copper-nickel selenide (Cu-Ni0.85Se) nanoparticle for synergistic therapy

Currently, finite intratumoral H₂O₂ content has restricted the efficacy of chemodynamic therapy (CDT). Here, Cu-Ni_0.85Se@PEG nanoparticles are constructed to display intracellular NIR-II photocatalytic H₂O₂ supplement. The formation mechanism is explored to discover that H₂O₂ generation is dominated by photo-excited electrons and dissolved O₂ via a typical sequential single-electron transfer process. Both density functional theory calculation and experimental data confirm its metallic feature that endows the great NIR-II absorption and photothermal conversion efficiency (59.6 %, 1064 nm). Furthermore, the photothermal-assisting consecutive interband and intraband transition in metallic catalyst contributes to the high redox capacity and efficient separation/transfer ability of photo-generated charges, boosting H₂O₂ production under 1064 nm laser irradiation. In addition, Cu-Ni_0.85Se@PEG possess mimic peroxidase and catalase activity, leading to in-situ H₂O₂ activation to produce ∙OH and O₂ for the enhanced CDT and hypoxia relief. What's more, the nanomaterials reveal novel biodegradation that is derived from oxidation from insolvable selenide into soluble selenate, resulting in elimination via feces and urine within 2 weeks. Synergistic CDT and photothermal therapy (PTT) further lead to great tumor inhibition and immune response for anti-tumor. The antitumor mechanism and the potential biological process also are investigated by high-throughput sequencing of expressed transcripts (RNAseq). The great treatment performance is responsible for the regulation of related oxidative stress and stimulus genes to induce organelle (mitochondrial) and membrane dysfunction. Besides, the synergistic therapy also can efficiently evoke immune response to further fight against tumor.