Insight Investigation of Active Palladium Surface Sites in Palladium-Ceria Catalysts for NO + CO Reaction

Electrothermal Water-Gas Shift Reaction at Room Temperature with a Silicomolybdate-Based Palladium Single-Atom Catalyst

The water-gas shift (WGS) reaction is often conducted at elevated temperature and requires energy-intensive separation of hydrogen (H₂ ) from methane (CH₄ ), carbon dioxide (CO₂ ), and residual carbon monoxide (CO). Designing processes to decouple CO oxidation and H₂ production provides an alternative strategy to obtain high-purity H₂ streams. We report an electrothermal WGS process combining thermal oxidation of CO on a silicomolybdic acid (SMA)-supported Pd single-atom catalyst (Pd₁ /CsSMA) and electrocatalytic H₂ evolution. The two half-reactions are coupled through phosphomolybdic acid (PMA) as a redox mediator at a moderate anodic potential of 0.6 V (versus Ag/AgCl). Under optimized conditions, our catalyst exhibited a TOF of 1.2 s^-1 with turnover numbers above 40 000 mol CO 2 ${{_{{\rm CO}{_{2}}}}}$  mol_Pd ^-1 achieving stable H₂ production with a purity consistently exceeding 99.99 %.

Three birds with one stone: oxygen self-supply engineering palladium nanocluster/titanium carbide hybrid for single-NIR laser-triggered synergistic photodynamic-photothermal therapy

As a key branch of the cross-discipline biophotonics, phototherapy, including photodynamic therapy (PDT), and photothermal therapy (PTT), is promising in biomedicine and visible light-driving PDT has been applied to clinical treatment. However, extensive applications of phototherapy are limited by the hypoxic microenvironment, laser penetration depth, and potential complexity for combined PDT/PTT. Thus, NIR-responsive oxygen self-supply nanocomposites functionalized with photosensitizers for achieving simultaneous in-depth PDT/PTT are urgently required. Herein, a multifunctional platform has been fabricated by co-immobilizing monodispersed ultrasmall Pd nanoclusters and a photosensitizer 5,10,15,20-Tetrakis (4-Aminophenyl)-21H,23H Porphyrin (Thp) on the surface of Ti3C2T x MXene nanosheets, generating the Pd-Thp-Ti3C2T x nanocomposite. Material characterization demonstrated that Pd nanoclusters and Thp were well-distributed on the MXene surface while MXene maintained its photothermal conversion efficiency and broad absorption. In this nanoplatform, irradiated by the single 808 nm laser, Pd selectively catalyzed the decomposition of H2O2 to O2, and O2 was continuously supplied to Thp for enhanced NIR-driving PDT. The in vivo fluorescence and photothermal imaging demonstrated the pronounced accumulation of nanocomposites in the tumor site. Both in vitro and in vivo results clearly demonstrated the nanocomposite had good biocompatibility, and that the synergistic PTT and enhanced PDT made apoptosis of the tumor cell achievable. This work not only proves this Pd-Thp-Ti3C2T x nanocomposite serves a promising solution for tumor hypoxia by inducing apoptosis of tumor cells with synergistic PTT and PDT, but also broadens the application of promising optical materials in biomedical field.

Enhanced Catalytic Activity Induced by the Nanostructuring Effect in Pd Decoration onto Doped Ceria Enabling an Origami Paper Analytical Device for High Performance of Amyloid-β Bioassay

In this work, we fabricated a novel origami paper-based analytical device (oPAD) assisted by the nanostructuring effect of in situ Pd decoration of Cu/Co-doped CeO₂ (CuCo-CeO₂-Pd) nanospheres, functionalized with their strongly enhanced electrocatalytic properties to realize an electrochemical and visual signal readout system in oPAD, for highly sensitive detection of amyloid-β (Aβ). The CuCo-CeO₂-Pd nanospheres were introduced as an enhanced "signal transducer layer" on account of the electron transfer acceleration caused by catalyzing glucose to produce H₂O₂ for differential pulse voltammetry signal readout and further 3,3'5,5'-tetramethylbenzidine (TMB) oxidation for colorimetric analysis. Meanwhile, for achieving superior performance of the proposed oPAD, in situ growth of urchin-like gold nanoparticles (Au NPs) onto cellulose fibers was adopted to improve "the recognition layer" in favor of immobilizing antibodies for targeting Aβ through specific antigen-antibody interactions. Combined with the delicate design of oPAD, exhibiting actuation of the conversion procedure between hydrophobicity and hydrophilicity on paper tabs in the assay process, the oPAD successfully enabled sensitive diagnosis of Aβ in a linear range from 1.0 pM to 100 nM with a limit of detection of 0.05 pM (S/N = 3) for electrochemical detection, providing a reliable strategy for quantifying the Aβ protein in clinical applications.

The contributions of distinct Pd surface sites in palladium–ceria catalysts to low-temperature CO oxidation

The low-temperature CO oxidation properties of Pd/CeO₂ catalysts can be correlated with the distribution of PdO_x/Pd–O–Ce species.

Oxidized Palladium Supported on Ceria Nanorods for Catalytic Aerobic Oxidation of Benzyl Alcohol to Benzaldehyde in Protic Solvents

In the present study, the catalytic activity of palladium oxide (PdOx) supported on ceria nanorods (CeO2-NR) for aerobic selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) was evaluated. The CeO2-NR was synthesized hydrothermally and the Pd(NO3)2 was deposited by a wet impregnation method, followed by calcination to acquire PdOx/CeO2-NR. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). In addition, the TPR-reduced PdOx/CeO2-NR (PdOx/CeO2-NR-Red) was studied by XRD, BET, and XPS. Characterizations showed the formation of CeO2-NR with (111) exposed plane and relatively high BET surface area. PdOx (x > 1) was detected to be the major oxide species on the PdOx/CeO2-NR. The activities of the catalysts in BnOH oxidation were evaluated using air, as an environmentally friendly oxidant, and various solvents. Effects of temperature, solvent nature and palladium oxidation state were investigated. The PdOx/CeO2-NR showed remarkable activity when protic solvents were utilized. The best result was achieved using PdOx/CeO2-NR and boiling ethanol as solvent, leading to 93% BnOH conversion and 96% selectivity toward PhCHO. A mechanistic hypothesis for BnOH oxidation with PdOx/CeO2-NR in ethanol is presented.

Support-Free Pd3 Co NCs as an Efficient Heterogeneous Nanocatalyst for New Organic Transformations of C-C Coupling Reactions

A support-free heterogeneous Pd₃ Co nanostructured composite (NC), synthesized through a hydrothermal route, acted as an effective catalytic system in multivariate Heck-, Sonogashira-, and Suzuki-type coupling reactions of iodonium ylides. The XPS analysis of the bimetallic Pd₃ Co NCs confirmed the elemental composition as 75 % palladium and 25 % cobalt. Furthermore, high-resolution (HR) TEM analysis confirmed the spherical morphology of the Pd₃ Co bimetallic nanoparticles. The average diameter of the NCs is 14.8 nm. The coupling reaction proceeded through the generation of α-iodoenones with simultaneous migration of the phenyl group, thereby giving a scaffold with higher atom economy. The heterogeneous Pd₃ Co NCs were recycled and reused without any significant change in catalytic ability for up to five reaction cycles. The high concentration of Pd and association of cobalt into the lattice of palladium appears to enhance its catalytic ability for the diverse coupling reactions in comparison with its monometallic counterparts as well as with bimetallic NCs with a comparatively lesser amount of Pd.

Catalytic NO reduction by CO over ceria–cobalt oxide catalysts

The effectiveness of the tandem catalysts was verified by a combination of Co₉₈Ce₂ for low temperature reactions and Co₁₅Ce₈₅ for high temperature reactions.