A novel CeO2 -x SnO2 /Ce2 Sn2 O7 pyrochlore cycle for enhanced solar thermochemical water splitting

Redox behavior of potassium doped and transition metal co-doped Ce0.75Zr0.25O2 for thermochemical H2O/CO2 splitting

CeO2 slow redox kinetics as well as low oxygen exchange ability limit its application as a catalyst in solar thermochemical two-step cycles. In this study, Ce0.75Zr0.25O2 catalysts doped with potassium or transition metals (Cu, Mn, Fe), as well as co-doped materials were synthesized. Samples were investigated by X-ray diffraction (XRD), N2 sorption (BET), as well as by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) to gain insight into surface and bulk features, which were connected to redox properties assessed both in a thermogravimetric (TG) balance and in a fixed bed reactor. Obtained results revealed that doping as well as co-doping with non-reducible K cations promoted the increase of both surface and bulk oxygen vacancies. Accordingly, K-doped and Fe-K co-doped materials show the best redox performances evidencing the highest reduction degree, the largest H2 amounts and the fastest kinetics, thus emerging as very interesting materials for solar thermochemical splitting cycles.

Label-Free and Ultrasensitive Electrochemiluminescent Immunosensor Based on Novel Luminophores of Ce2Sn2O7 Nanocubes

In this research article, a novel and simple label-free electrochemiluminescence (ECL) immunosensor using cerium stannite (Ce₂Sn₂O₇) nanocubes as brand-new ECL emitters has been suggested for the first time. Ce₂Sn₂O₇ nanocubes prepared by a simple hydrothermal method displayed bright ECL emission, promising biocompatibility, low noxiousness, and perfect stability. On comparison of ECL and photoluminescence (PL) spectra, a surface-state mechanism was proposed to be involved in the ECL emission. After aminofunctionalization with 3-aminopropyltriethoxysilane (APTES), Ce₂Sn₂O₇ could be decorated with gold nanoparticles through Au-NH₂ covalent linkage, which yielded Au@Ce₂Sn₂O₇ nanocomposites and further enhanced the ECL emission. To confirm the proposed immunosensor feasibility, carcinoembryonic antigen (CEA) was employed as an exemplary analyte. Based on the abovementioned points, our fabricated immunosensor improved the ECL performance to CEA concentrations in a linear range of 0.001-70 ng/mL with a low limit of detection of 0.53 pg/mL (S/N = 3). With outstanding stability, reproducibility, and specificity, this method is expected to be an innovative one for sensitive analyses of CEA and other biomarkers in real samples.

CeTi2O6-A Promising Oxide for Solar Thermochemical Hydrogen Production

A large entropy of reduction is crucial in achieving materials capable of high-efficiency solar thermochemical hydrogen (STCH) production through two-step thermochemical water splitting cycles. We have recently demonstrated that the onsite electronic entropy of reduction attains an extreme value of 4.26 k_B at 1500 K in Ce⁴⁺ → Ce³⁺ redox reactions, which explains the high performance and uniqueness of CeO₂ as an archetypal STCH material. However, ceria requires high temperatures (T > 1500 °C) to achieve a reasonable reduction extent because of its large reduction enthalpy, which is a major obstacle in practical applications. Therefore, new materials with a large entropy of reduction and lower reduction enthalpy are required. Here, we perform a systematic screening to search for Ce⁴⁺-based oxides which possess thermodynamics superior to CeO₂ for STCH production. We first search the Inorganic Crystal Structure Database (ICSD) and literature for Ce⁴⁺-based oxides and subsequently use density functional theory to compute their reduction enthalpies (i.e., oxygen vacancy formation energies). We find that CeTi₂O₆ with the brannerite structure is the most promising candidate for STCH because it possesses three essential characteristics of an STCH material: (i) a smaller reduction enthalpy compared to ceria yet large enough to split water, (ii) a high thermal stability, as reported experimentally, and (iii) a large entropy of reduction associated with Ce⁴⁺ → Ce³⁺ redox. Our proposed design strategy suggests that further exploration of Ce⁴⁺ oxides for STCH production is warranted.