▶ Ultrapure hydrogen at a stable rate of 25
mL/min was produced from a novel solid-state NaBH
4 composite. ▶ No mechanical control system was in need to maintain the stable production of hydrogen ...from this solid NaBH
4 chemical-hydride system. ▶ A cellular phone was successfully powered at 2
W for 2
h by a PEMFC stack fed with the produced hydrogen. ▶ The generated hydrogen could be successfully converted to electric energy by the PEMFC stack to recharge a 3.7
V/1100
mAh Li-ion battery in 2
h.
Hydrolysis of sodium borohydride (NaBH
4) is a promising method for on-board hydrogen supply to polymer electrolyte membrane fuel cells (PEMFC). This article presents an attempt to design a novel solid-state NaBH
4 composite, which is made up of NaBH
4 powder, Co
2+/IR-120 catalyst and silicone rubber, for hydrogen generator. The silicone rubber can act as a stabilizer in the solid-state NaBH
4 composite because of its surface hydrophobicity leading to reduced diffusion rate of water into the composite. The solid-state NaBH
4 composite can produce hydrogen stably near 25
mL
min
−1 for at least 2
h without employment of any mechanical control system. Using the hydrogen generated from the solid-state NaBH
4 composite, a 2
W PEMFC stack is successfully operated to power a cellular phone.
Nanostructured apatite has been widely used as a bone substitute material due to its biological similarity to the natural bone mineral. To enhance further the biomineralisation and introduce ...bactericidal properly into HA, co-substitution of Ag and Si has been investigated. A co-substituted nanosized apatite (Ag/Si-HA) containing Ag (0.3 wt %) and Si (0.8 wt %) was synthesized by an aqueous precipitation technique. Bone-apatite mimicking morphology of dimensions ~50 nm in length and ~10 nm in width was observed for the Ag/Si-HA nano powder. XRF detected the presence of Ag and Si in phase-pure Ag/Si-HA. The Ag/Si-HA nano powders were then compacted and sintered at various temperatures (900-1300 °C) and found to achieve a maximum densification of 93 % at 1300 °C, with a gram size of approximately 1 μm. Phase-purity was maintained up to a temperature of 1300 °C, as observed from the XRD pattern. This study thus demonstrated that a phase-pure Ag/Si-HA was synthesized via an aqueous precipitation technique.
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