Preparation of N3- Doped WO3 Photocatalyst by Thermal Decomposition of Ammonium Paratungstate
Takeuchi, Masato, et al. Applied Catalysis B: Environmental, 2011, 110, 1-5.
The preparation of nitrogen-doped WO3 (N-WO3) photocatalyst was achieved by thermal decomposition of ammonium paratungstate [(NH4)10W12O41·5H2O]. The prepared N-WO3 can effectively absorb visible light in the longer wavelength region. After further depositing Pt particles on the surface of N-WO3, Pt/N-WO3 with photocatalytic activity was obtained, which can decompose about 100 mmol/L methanol.
Synthesis of Pt/N-WO3 photocatalyst via ammonium paratungstate
· The N-doped WO3 powders were produced by heating ammonium paratungstate in an air environment at temperatures ranging from 473K to 1073K.
· Following this, a small quantity of Pt particles was deposited onto the N-doped WO3 surface using a photodeposition technique involving H2PtCl6·6H2O in a solution of methanol and water (methanol/H2O = 50 vol%).
· The resulting samples were labeled as Pt(X)/N-WO3(Y) (X representing the percentage of Pt loaded, and Y representing the calcination temperature in Kelvin). A commercially available N-free WO3 powder was used as a control for comparison.
· The photocatalytic reactivity ofthe Pt/N-WO3 samples was evaluated by decomposition of gaseous methanol under visible light or sunlight irradiations.
Ammonium Paratungstate Used for the Synthesis of Single-Phase α-Tungsten Nanopowder
Shin, Dongyoon, et al. Korean Journal of Metals and Materials, 2020, 58.(11), 798-807.
Using ammonium paratungstate (APT) as raw material, single-phase α-W (α-W) nanopowder can be successfully prepared through radio frequency induction thermal plasma and thermochemical reduction treatment .
Synthesis procedure of α-W nanopowder
· Initially, the first step involved injecting the APT precursor into the RF induction thermal plasma under specific experimental conditions. Prior to injection, the reactor chamber was purged with Ar for 30 minutes and pre-conditioned to the plasma power specified for 20 minutes until reaching a steady state.
· The precursor particles were carried into the plasma flame with the carrier gas using a powder-feeding system, vaporized by the plasma flame, and quickly quenched by the quenching gas to enhance the nucleation kinetics of nanoparticle synthesis. The resultant nanoparticles were collected with powder-collecting sintered-metal filters with a pore size of 1 μm.
· In the second step, the nanopowder synthesized in the first phase via RF induction thermal plasma was subjected to thermochemical reduction through annealing in an H2 reductive atmosphere. The conditions for H2 reductive annealing included an H2 flow rate of 0.5 L/min, a temperature ranging from 600-900 °C, and a 10-minute process time.
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