68
6 Hydrogen from Miscellaneous Sources and Nanotechnology
6.4 Ammonia/Ammonium-Derivative-Based Hydrogen
Generation
As stated, earlier ammonia and its derivative are important source of hydrogen
liberation. Some of the ammonia derivatives employ nanotechnology for hydrogen
generation.
Serdar et al. have used ceria-supported rhodium nanomaterials for the hydrolysis
of ammonia borane to liberate hydrogen. The researchers elaborated the effect of
different oxides on the catalytic ability of rhodium nanoparticles during the hydrolysis of ammonia borane for hydrogen generation. Different oxide supports like CeO 2 ,
SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , and HfO 2 were used. However, ceria offered the best
catalytic with rhodium nanoparticles for ammonia borane hydrolysis. The said nanomaterial consisted of Rh(0) nanoparticles restrained on nanoceria, i.e., Rh(0)/CeO 2 .
The nanomaterials were synthesized via impregnation process. In practice, the Rh(III)
ions were allowed to deposit on the ceria surface by using RhCl 3 ·3H 2 O, and the deposition was followed by the reduction of ions to Rh(0) with sodium borohydride at
room temperature. The nanomaterials thus obtained were separated via centrifugation
and analyzed with inductively coupled plasma optical emission spectroscopy (ICPOES), TEM, SEM, and XPS. The catalytic ability of the prepared nanomaterials was
determined at different wt.% loading of the Rh nanoparticles in nanoceria for the
hydrolysis of ammonia borane. The catalysts depicted best activity with 0.1 wt.%
loading of Rh nanoparticles. The nanoparticles showed record turnover frequency
value of 2010/min at ~25 °C. The remarkable catalytic activity of the material is associated to the reducible nature of nanoceria. The prepared nanomaterials are reusable
catalysts with the ability to retain 67% initial activity even in the fifth cycle [35].
Another investigation has reported the use of Pd nanoparticles maintained on
cobalt ferrite (Pd(0)/CoFe 2 O 4 ) as a catalyst for the hydrogen generation via hydrolysis of ammonia borane. The catalyst depicted turnover frequency of 290/min at
25 °C. The stability of the substance was enhanced with the use of polydopaminecovered cobalt ferrite in place of exposed cobalt ferrite. The coating of polydopamine
was obtained via pH-dependent self-polymerization with dopamine hydrochloride
at 25 °C. The Pd nanoparticles were loaded on the support material (polydopaminecoated cobalt ferrite) via two-step process involving impregnation and reduction. The
materials were characterized with Fourier transform infrared (FTIR), XRD, attenuated total reflectance [36], TEM, SEM, EDS, ICP-OES, and Brunauer–Emmett–
Teller (BET). The analyzation revealed that Pd nanoparticles have average size of
~1.4 nm and have complete dispersion on polydopamine layer, where the thickness
of the layer was found to be ~ 8.6 nm. The value of turnover frequency was determined to 175/min at ~25.0 °C. The chemical equation for the reaction can be given
as [37].
NBH 6 + 2H 2 O → NH
4+
+ BO
2−
+ 3H 2
6 Hydrogen from Miscellaneous Sources and Nanotechnology
6.4 Ammonia/Ammonium-Derivative-Based Hydrogen
Generation
As stated, earlier ammonia and its derivative are important source of hydrogen
liberation. Some of the ammonia derivatives employ nanotechnology for hydrogen
generation.
Serdar et al. have used ceria-supported rhodium nanomaterials for the hydrolysis
of ammonia borane to liberate hydrogen. The researchers elaborated the effect of
different oxides on the catalytic ability of rhodium nanoparticles during the hydrolysis of ammonia borane for hydrogen generation. Different oxide supports like CeO 2 ,
SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , and HfO 2 were used. However, ceria offered the best
catalytic with rhodium nanoparticles for ammonia borane hydrolysis. The said nanomaterial consisted of Rh(0) nanoparticles restrained on nanoceria, i.e., Rh(0)/CeO 2 .
The nanomaterials were synthesized via impregnation process. In practice, the Rh(III)
ions were allowed to deposit on the ceria surface by using RhCl 3 ·3H 2 O, and the deposition was followed by the reduction of ions to Rh(0) with sodium borohydride at
room temperature. The nanomaterials thus obtained were separated via centrifugation
and analyzed with inductively coupled plasma optical emission spectroscopy (ICPOES), TEM, SEM, and XPS. The catalytic ability of the prepared nanomaterials was
determined at different wt.% loading of the Rh nanoparticles in nanoceria for the
hydrolysis of ammonia borane. The catalysts depicted best activity with 0.1 wt.%
loading of Rh nanoparticles. The nanoparticles showed record turnover frequency
value of 2010/min at ~25 °C. The remarkable catalytic activity of the material is associated to the reducible nature of nanoceria. The prepared nanomaterials are reusable
catalysts with the ability to retain 67% initial activity even in the fifth cycle [35].
Another investigation has reported the use of Pd nanoparticles maintained on
cobalt ferrite (Pd(0)/CoFe 2 O 4 ) as a catalyst for the hydrogen generation via hydrolysis of ammonia borane. The catalyst depicted turnover frequency of 290/min at
25 °C. The stability of the substance was enhanced with the use of polydopaminecovered cobalt ferrite in place of exposed cobalt ferrite. The coating of polydopamine
was obtained via pH-dependent self-polymerization with dopamine hydrochloride
at 25 °C. The Pd nanoparticles were loaded on the support material (polydopaminecoated cobalt ferrite) via two-step process involving impregnation and reduction. The
materials were characterized with Fourier transform infrared (FTIR), XRD, attenuated total reflectance [36], TEM, SEM, EDS, ICP-OES, and Brunauer–Emmett–
Teller (BET). The analyzation revealed that Pd nanoparticles have average size of
~1.4 nm and have complete dispersion on polydopamine layer, where the thickness
of the layer was found to be ~ 8.6 nm. The value of turnover frequency was determined to 175/min at ~25.0 °C. The chemical equation for the reaction can be given
as [37].
NBH 6 + 2H 2 O → NH
4+
+ BO
2−
+ 3H 2