Precise Modulation of Triple-Phase Boundaries towards a Highly Functional Exsolved Catalyst for Dry Reforming of Methane under a Dilution-Free System

Dry reforming of methane (DRM) has been emerging as a viable solution to achieving carbon neutrality enhanced by the Paris Agreement as it converts the greenhouse gases of CO2 and CH4 into industrially useful syngas. However, there have been limited studies on the DRM catalyst under mild operating conditions with a high dilution gas ratio due to their deactivation from carbon coking and metal sintering. Herein, we apply the triple-phase boundary (TPB) concept to DRM catalyst via exsolution phenomenon that can secure elongated TPB by controlling the Fe-doping ratio in perovskite oxide. Remarkably, the exsolved catalyst with prolongated TPB shows exceptional CO2 and CH4 conversion rates of 95.9 % and 91.6 %, respectively, stable for 1000 hours under a dilution-free system. DFT calculations confirm that the Lewis acid of support and Lewis base of metal at the TPB promote the adsorption of reactants, resulting in lowering the overall CO2 dissociation and CH4 dehydrogenation energy

Unveiling the key factor for the phase reconstruction and exsolved metallic particle distribution in perovskites

To significantly increase the amount of exsolved particles, the complete phase reconstruction from simple perovskite to Ruddlesden-Popper (R-P) perovskite is greatly desirable. However, a comprehensive understanding of key parameters affecting the phase reconstruction to R-P perovskite is still unexplored. Herein, we propose the Gibbs free energy for oxygen vacancy formation in Pr-0.5(Ba/Sr)(0.5)TO3-delta (T = Mn, Fe, Co, and Ni) as the important factor in determining the type of phase reconstruction. Furthermore, using in-situ temperature & environment-controlled X-ray diffraction measurements, we report the phase diagram and optimum 'x' range required for the complete phase reconstruction to R-P perovskite in Pr0.5Ba0.5-xSrxFeO3-delta system. Among the Pr0.5Ba0.5-xSrxFeO3-delta, (Pr0.5Ba0.2Sr0.3)(2)FeO4+delta - Fe metal demonstrates the smallest size of exsolved Fe metal particles when the phase reconstruction occurs under reducing condition. The exsolved nano-Fe metal particles exhibit high particle density and are well-distributed on the perovskite surface, showing great catalytic activity in fuel cell and syngas production. The complete phase reconstruction to Ruddlesden-Popper perovskite is greatly desirable to increase the exsolved particle distribution. Here, the authors report a key factor for the complete phase reconstruction in perovskites, leading to good catalytic activity in fuel cell and syngas production

Design Optimization of Silicon Single Photon Avalanche Diode with for High Photon Detection and Low Crosstalk Probabilities

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Utilization of an Isovalent Doping Strategy in Cobalt-Free Ferrites for Highly Active and Stable Solid Oxide Fuel Cell Cathodes

Cobalt-free ferrites are attracting tremendous spotlight as prospective solid oxide fuel cell cathode material nowadays owing to their good structural stability and great thermo-mechanical compatibility with electrolytes. Nevertheless, the oxygen reduction reaction (ORR) activity for cobalt-free ferrites is comparatively lower than that for cobalt-based cathodes. Hence, an isovalent doping strategy is an attractive option to significantly promote the ORR activity of cobalt-free ferrites. Herein, we systematically investigate the optimal Sr2+ concentration in cobalt-free Pr0.5Ba0.5-ySryFeO3-delta (PBSF series). The replacement of Ba2+ by Sr2+ is beneficial to decrease the thermal expansion coefficient. Moreover, the Pr0.5Ba0.2Sr0.3FeO3-delta material demonstrates the highest electrical conductivity and the lowest area-specific resistance (R-p, 0.027 Omega cm(2), 700 degrees C) among the PBSF series. To elucidate the close relationship between the Rp value and the electrical conductivity in the PBSF series, distribution of relaxation time analysis and density functional theory calculations are utilized. Furthermore, outstanding cell operational durability is exhibited for 200 h

Systematically Optimized Bilayered Electron Transport Layer for Highly Efficient Planar Perovskite Solar Cells (n= 21.1%)

Understanding and controlling interfacial charge transfer at the heterojunction of optoelectronic devices is currently receiving extensive interest. Here, we study the parameters that can influence the electron extraction in planar perovskite solar cells (P-PSCs) using spin-coated SnO2 and TiO2, anodized-TiO2 (a-TiO2), and bilayered electron transport layers (ETL) composed of SnO2 and TiO2 or SnO2 on a-TiO2 (SnO2@a-TiO2). These are the varied free energy difference (ΔG) values between the ETL and perovskites, electron mobility (μe) of the ETL, and quality of physical contact between the ETL and fluorine-doped tin oxide (FTO). Among the various ETLs, the bilayered ETL (SnO2@a-TiO2) gives a large ΔG as well as defect-free physical contact. The resulting P-PSC exhibits a PCE of 21.1% and stabilized efficiency of 20.2% with reduced hysteresis. This result emphasizes that a large free energy difference (ΔG) value plays an important role in electron extraction. More importantly, the defect-free physical contact is also crucial for achieving improved electron extraction.1127sciescopu

Titanium Monoxide with in Situ Grown Rutile TiO2Nanothorns as a Heterostructured Job-Sharing Anode Material for Lithium-Ion Storage

Developing high-performance anodes is highly desired to meet the recent ever-increasing demands for high-energy lithium-ion batteries (LIBs). Titanium dioxide (TiO2) shows extremely stable performance as an anode material in LIBs, but its intrinsic structural limit critically inhibits the full utilization of the TiO2 material. Herein, we report a uniquely integrated heterostructure of rutile TiO2 (r-TiO2) nanothorns grown in situ over a new porous and conductive cubic crystalline titanium monoxide (TiO) core. The new cubic crystalline TiO is prepared from phase transformation of anatase TiO2 by pyrolysis with Mg metal at 650 °C, and subsequent oxidative HCl treatment enables in situ growth of r-TiO2 nanothorns on the surface of the porous TiO. Interestingly, the mixed-phased novel hybrid as an anode exhibits a new Li-ion charging mechanism consisting of two independent reactions of intercalation and pseudocapacitive interaction corresponding to the two different phases of r-TiO2 and TiO, respectively, in the composite for Li-ion storage. Thus, it illustrates high reversible capacity and almost no capacity decay during 1000 cycles at a high current density of 20 C (4000 mA g-1), overcoming the issues of conventional TiO2. In particular, the excellent rate capability along with a long cycle life enables the new hybrid to have ultrafast charging of the system. Furthermore, unlike a conventional TiO2 anode working in the potential range (1.0-3.0 V), the hybrid with the job-sharing property exhibits stable charge-discharge performance over a wider potential window range of 0.01-3.0 V, particularly even in the low potential range of 0.01-1.0 V. All the properties including the wider potential window allow the hybrid to realize the highest electrochemical performance that titanium oxides have ever achieved so far. © 2022 American Chemical Society.FALS

Concurrent promotion of phase transition and bimetallic nanocatalyst exsolution in perovskite oxides driven by Pd doping to achieve highly active bifunctional fuel electrodes for reversible solid oxide electrochemical cells

The reducibility of B-site elements in perovskite (ABO3) structures is one of the paramount factors that promote the in-situ exsolution of metallic nanocatalysts, and the phase transition of the support to a more stable structure under solid oxide cell (SOC) fuel electrode operating conditions. Herein, we develop a highly catalytically active and durable perovskite-based fuel electrode material & mdash;La0.6Sr0.4Co0.15Fe0.8Pd0.05O3-delta (LSCFP)& mdash;for reversible SOCs. The LSCFP material under the fuel electrode condition is fully transformed into a stable Ruddlesden-Popper phase decorated by bimetallic Co-Fe nanocatalysts. The SOC with LSCFP fuel electrode yielded outstanding performances in both fuel cell (2.00 W cm-2) and electrolysis cell (2.23 A/cm(2) at 1.3 V) modes at 850 ?C, with remarkable reversible-cyclic stability. These results clearly demonstrate that the novel LSCFP capable of concurrent phase transition and bimetallic exsolution in the reducing condition is a highly prospective candidate as a bifunctional fuel electrode for reversible SOCs