fElectrochemical energy production and storage at large scale and low cost, is a critical bottleneck in renewable energy systems. Oxides and lithium transition metal phosphates have been researched for over two decades and many technologies based on them exist. Much less work has been done investigating the use of sodium phosphates for energy storage. In this work, the synthesis of sodium nickel phosphate at different temperatures is performed and its performance evaluated for supercapacitor applications. The electronic properties of polycrystalline NaNiPO 4 polymorphs, triphylite and maricite, t-and m-NaNiPO 4 are calculated by means of first-principle calculations based on spin-polarized Density Functional Theory (DFT). The structure and morphology of the polymorphs were characterized and validated experimentally and it is shown that the sodium nickel phosphate (NaNiPO 4 ) exists in two different forms (triphylite and maricite), depending on the synthetic temperature (300-550°C). The as-prepared and triphylite forms of NaNiPO 4 vs. activated carbon in 2 M NaOH exhibit the maximum specific capacitance of 125 F g −1 and 85 F g −1 respectively, at 1 A g −1 ; both having excellent cycling stability with retention of 99% capacity up to 2000 cycles. The maricite form showed 70 F g −1 with a significant drop in capacity after just 50 cycles.These results reveal that the synthesized triphylite showed a high performance energy density of 44 Wh kg −1 which is attributed to the hierarchical structure of the porous NaNiPO 4 nanosheets. At a higher temperature (>400°C) the maricite form of NaNiPO 4 possesses a nanoplate-like (coarse and blocky) structure with a large skewing at the intermediate frequency that is not tolerant of cycling. Computed results for the sodium nickel phosphate polymorphs and the electrochemical experimental results are in good agreement.

A facile solvent evaporation induced self-assembly (SEISA) strategy was developed to synthesize mesoporous N-doped anatase TiO 2 (SE-meso-TON) using a single organic complex precursor derived in situ from titanium butoxide and ethylenediamine in ethanol solution. After the evaporation of ethanol in a fume hood and subsequent calcinations at 450 C, the obtained N-doped TiO 2 (meso-TON)anatase was of finite crystallite size, developed porosity, large surface area (101 m 2 g À1) and extended light absorption in the visible region. This SE-meso-TON also showed superior photocatalytic activity to the SG-meso-TON anatase prepared via sol-gel synthesis. On the basis of characterization results from XRD, XPS, N 2 adsorption-desorption and ESR, the enhanced visible-light-responsive photocatalytic activity of SE-meso-TON was assigned to its developed mesoporosity and reduced oxygen vacancies. IntroductionMotivated by the discovery of the excellent visible-lightresponse of nitrogen-doped TiO 2 (TiO 2Àx N x , hereaer, TON),various nonmetal dopants (e.g. N, C, S, P, and halogen elements) have been extensively attempted to be doped or codoped into the TiO 2 matrix for narrowing its wide bandgap ($3.2 eV) and thus harvesting visible light. 3 Among those doped TiO 2 materials, TON is more desirable due to its low energy requirement for doping and superb performance in photovoltaic and photocatalytic applications.2,4-7 In practice, the mesoporous TON (meso-TON) is plausible because its large specic surface area (SSA) and developed porosity favour solar energy conversion. 4,8 Despite the fact that enormous advances have been achieved in the control of N-doping level, morphology, crystallite size and crystallinity of TiO 2Àx N x , 9-11 synthesis of mesoporous TiO 2Àx N x (meso-TON) remains a great challenge because the mesoporous structure is prone to collapse during nitriding and crystallization at elevated temperature. 8,12-14Ammonolysis is the most used nitriding technique for preparation of TON, though it occurs above 500 C. 2,10,13 Such a high ammonolysis temperature inevitably destructs the porosity of the primitive meso-TiO 2 , induces phase transition and hampers its applications in thin lm devices.2,10 In order to retain its developed porosity, a few low-temperature methodologies, such as sol-gel, 9 hydrothermal or solvothermal combined with post-nitriding, 10,11 have been developed for preparing meso-TON. In those methodologies, the involved solvent, surfactant template and chemical sources of Ti and N controlled the hydrolysis, nitriding and crystallization processes and thus determined the mesoporosity of the resultant TON. 15,16 In particular, the alternative nitrogen sources to NH 3 , such as NH 4 Cl, 13 urea, 15,17,18 HMT, 19 glycine 16 and thiourea, 20 are plausible for realizing low-temperature nitriding. Solvent evaporation induced assembly (SEISA) has been demonstrated to be an excellent route to prepare meso-TiO 2 thin lms, 12 in terms of its great exibility in handling the synthesis system (solvents, su...

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Dry reforming of methane (DRM) is considered a high endothermic reaction with operating temperatures between 700 and 1000°C to achieve high equilibrium conversion of CH 4 and CO 2 to the syngas (H 2 and CO). The conventional catalysts used for DRM are Ni-based catalysts. However, many of these catalysts suffer from the short longevity due to carbon deposition. This study aims to evaluate the effect of La and Ca as promoters for Nibased catalysts supported on two different zeolite supports, ZL (A) (BET surface area = 925 m 2 /g, SiO 2 /Al 2 O 3 mol ratio = 5.1), and ZL (B) (BET surface area = 730 m 2 /g, SiO 2 /Al 2 O 3 mol ratio = 12), for DRM. The physicochemical properties of the prepared catalysts were characterized with XRD, BET, TEM and TGA. These catalysts were tested for DRM in a microtubular reactor at reaction conditions of 700°C. The catalyst activity results show that the catalysts Ni/ZL (B) and Ca-Ni/ZL (B) give the highest methane conversion (60 %) with less time on stream stability compared with promoted Ni on ZL (A). In contrast, La-containing catalysts, La-Ni/ZL (B), show more time on stream stability with minimum carbon content for the spent catalyst indicating the enhancement of the promoters to the Ni/ZL (A) and (B), but with less catalytic activity performance in terms of methane and carbon dioxide conversions due to rapid catalyst deactivation.

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