Engineering oxygen vacancies on Tb-doped ceria supported Pt catalyst for hydrogen production through steam reforming of long-chain hydrocarbon fuels

Steam reforming of long-chain hydrocarbon fuels for hydrogen production has received great attention for thermal management of the hypersonic vehicle and fuel-cell application.In this work,Pt catalysts supported on CeO_(2)and Tb-doped CeO_(2)were prepared by a precipitation method.The physical structure and chemical properties of the as-prepared catalysts were characterized by powder X-ray diffraction,scanning electron microscopy,transmission electron microscopy,Raman spectroscopy,H_(2)temperature programmed reduction,and X-ray photoelectron spectroscopy.The results show that Tb-doped CeO_(2)supported Pt possesses abundant surface oxygen vacancies,good inhibition of ceria sintering,and strong metal-support interaction compared with CeO_(2)supported Pt.The catalytic performance of hydrogen production via steam reforming of long-chain hydrocarbon fuels(n-dodecane)was tested.Compared with 2Pt/CeO_(2),2Pt/Ce_(0.9)Tb_(0.1)O_(2),and 2Pt/Ce_(0.5)Tb_(0.5)O_(2),the 2Pt/Ce_(0.7)Tb_(0.3)O_(2)has higher activity and stability for hydrogen production,on which the conversion of n-dodecane was maintained at about 53.2%after 600 min reaction under 700℃at liquid space velocity of 9 ml·g^(-1)·h^(-1).2Pt/CeO_(2)rapidly deactivated,the conversion of n-dodecane was reduced to only 41.6%after 600 min.

TiO_(2)Electron Transport Layer with p-n Homojunctions for Efficient and Stable Perovskite Solar Cells

Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport and thus recombination loss at buried interface.Herein,we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO_(2)ETL to accelerate electron transport in PSCs,through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude.Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO_(2)ETL,but the fabrication of perovskite films with larger-grain and the less-trap-states.The embedded p-n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs,favoring for the reduced voltage deficit of PSCs.Benefiting from these merits,the formamidinium lead iodide(FAPbI_(3))PSCs employing such ETLs deliver a champion efficiency of 25.50%,along with much-improved device stability under harsh conditions,i.e.,maintain over 95%of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h,as well as mixed-cation PSCs with a champion efficiency of 22.02%and over 3000 h of ambient storage under humidity stability of 40%.Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics.

Relationship between hydrogenation degree and pyrolysis performance of jet fuel

Understanding the relationship between the chemical composition and pyrolysis performance of endothermic hydrocarbon fuel(EHF) is of great significance for the design and optimization of advanced EHFs. In this work, the effect of deep hydrogenation on the pyrolysis of commercial RP-3 is investigated.Fuels with different hydrogenation degrees were obtained by the partially and completely catalytic hydrogenation and their pyrolysis performances were investigated using an apparatus equipped with an electrically heated tubular reactor. The results show that with the increase of hydrogenation degree, fuel conversion almost remains constant during the pyrolysis process(500-650°C, 4 MPa);however, the heat sink increases slightly, and the anti-coking performance significantly improves, which are highly related to their H/C ratios. Detailed characterisations reveal that the difference of the pyrolysis performance can be ascribed to the content of aromatics and cycloalkanes: the former are prone to initiate secondary reactions to form coking precursors, while the latter could act as the hydrogen donor and release hydrogen, which will terminate the radical propagation reactions and suppress the coke deposition. This work should provide the guidance for upgrading EHFs by modulating the composition of EHFs.

Highly dispersible cerium-oxide modified Ni/SBA-15 for steam reforming of bio-mass based JP10

Ni/SBA-15 modified by highly dispersed cerium-oxide was prepared with the aid of sucrose for steam reforming of JP10(C_(10)H(16)).Their characterization showed that addition of appropriate amount ceria led to the formation of highly dispersed CeO_(2)and Ni,and the CeO_(2)covered smaller nickel particles like strawberry seeds to form much more interface between them.Their catalytic activity exhibited higher stability over time on stream of 6.5 h with conversion higher than 95%and higher carbon resistance(mass loss less than 4.5%by TG),which may derive from good properties below:(1)much more interface enhanced cooperation effect and increased turnover frequency at the interface;(2)the stronger interaction between Ni and ceria to suppress sintering by formation of Ni-O-Ce solid solution;(3)the large amount of oxygen vacancies from the formation of Ni-O-Ce solid solution and highly dispersed CeO_(2)to facilitate the water-gas-shift reaction and carbon removal.

Ni-Doped BiVO4 with V4+ Species and Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting

Bismuth vanadate is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its activity and stability need to be further improved. In this work, we synthesized Ni-doped BiVO 4 abundant with V 4+ species and oxygen defects through an in situ electrodeposition method. The eff ective doping can decrease the particle size of BiVO 4 and lead to the formation of V 4+ species/oxygen defects. Accordingly, the doped and defective BiVO 4 showed high optical absorption and rapid charge transfer, and further showed much higher PEC activity than pure BiVO 4 . Specifi cally, 5-Ni-BiVO 4 exhibits the highest activity in PEC water splitting, with a photocurrent of 2.39 mA/cm 2 at 1.23 V versus RHE (the reversible hydrogen electrode), which is 2.5 times higher than pure BiVO 4 (0.94 mA/cm 2 ), and much higher incident photon-to-current effi ciency (IPCE) value of 45%(while only 25% for BiVO 4 at ca. 400 nm). This work provides an in situ method for the development of a high-performance photoanode.

Fabrication and performance evaluation of GaN thermal neutron detectors with bm^6LiF conversion

A GaN-based pin neutron detector with a 6LiF conversion layer was fabricated, and can be used to detect thermal neutrons. Measurement of the electrical characteristic of the GaN-based pin neutron detector showed that the reverse leakage current of the neutron detector was reduced significantly after deposition of a 6LiF conversion layer on the detector surface. The thermal neutrons used in this experiment were obtained from an 241Am-Be fast neutron source after being moderated by 100-mm-thick high-density polyethylene. The experimental results show that the detector with 16.9-μm thick 6LiF achieved a maximum neutron detection efficiency of 1.9% at a reverse bias of 0 V, which is less than the theoretical detection efficiency of 4.1% calculated for our GaN neutron detectors.

Bifunctional catalysts of Co3O4@GCN tubular nanostructured （TNS） hybrids for oxygen and hydrogen evolution reactions

Catalysts for oxygen and hydrogen evolution reactions （OER/HER） are at the heart of renewable green energy sources such as water splitting. Although incredible efforts have been made to develop efficient catalysts for OER and HER, great challenges still remain in the development of bifunctional catalysts. Here, we report a novel hybrid of Co3O4 embedded in tubular nanostructures of graphitic carbon nitride （GCN） and synthesized through a facile, large-scale chemical method at low temperature. Strong synergistic effects between Co3O4 and GCN resulted in excellent performance as a bifunctional catalyst for OER and HER. The high surface area, unique tubular nanostructure, and composition of the hybrid made all redox sites easily available for catalysis and provided faster ionic and electronic conduction. The Co3O4@GCN tubular nanostructured （TNS） hybrid exhibited the lowest overpotential （0.12 V） and excellent current density （147 mA/cm^2） in OER, better than benchmarks IrO2 and RuO2, and with superior durability in alkaline media. Furthermore, the Co3O4@GCN TNS hybrid demonstrated excellent performance in HER, with a much lower onset and overpotential, and a stable current density. It is expected that the Co3O4@GCN TNS hybrid developed in this study will be an attractive alternative to noble metals catalysts in large scale water splitting and fuel cells.

Catalytic cracking of endothermic fuels in coated tube reactor

Suspensoid of HZSM-5 or HY zeolites mixed with a self-made ceramic-like binder was coated on the inner wall of a tubular reactor by gas-aided fluid displacement technology.The coated zeolites were characterized by means of X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The coating thickness is 10–20 mm and the particle size of the zeolites is in the range of 1–5 mm.In the coated reactor,cracking of endothermic fuels including n-dodecane and aviation fuel RP-3 was carried out separately under supercritical conditions at 600uC and 625uC to investigate their heat sinks and conversion of catalytic reactions.For the reaction catalyzed by HY(25%mass fraction)coating,the heat sink capacity of ndodecane are 815.7 and 901.9 kJ/kg higher than that of the bare tube at 600uC and at 625uC,respectively.Conversion of n-dodecane also increases from 42%to 60%at 600uC and from 66%to 80%at 625uC.The coated zeolite can significantly inhibit the carbon deposition during supercritical cracking reactions.