The application of DC electric field to the metal catalyst supported on semi-conductors induces surface protonics derived from water or hydrogen. Protons collide with reactants such as methane on the catalyst surface and promote the dissociative adsorption for stable intermediates even at low temperatures. Surface protonics creates a novel catalytic reaction mechanism and enhances heterogeneous catalytic reactions for hydrogen production.
The in-liquid plasma process has been utilized to produce hydrogen gas from various liquids such as hydrocarbon and alcohol liquids, electrolytes, waste oil, biomass solutions, including cellulose and lignin. Using this technology, zero-emission hydrogen generation could become possible because it enables liquids to be directly broken down by plasma, making possible the decomposition of waste substances while producing useful materials. Here, we will discuss a variety of applications of the in-liquid plasma method such as for hydrogen production from waste liquids or non-edible biomass, Methane Hydrate (MH). Utilizing in-liquid plasma for the decomposition of waste oil or other such organic liquids can generate hydrogen gas at purities of 42 to 82% and solid carbon at the same time. This method has a hydrogen gas production rate that is from 30% to the same order as that of the electrolysis of alkaline water.
An efficient device for hydrogen production from ammonia has been developed, which is an original pulsed plasma reactor with a hydrogen separation membrane. Ammonia was converted to hydrogen by the electron impact in the plasma, and the reaction mechanism was elucidated in detail by elementary reaction simulation. The hydrogen production rate was dominated by the ammonia concentration, the flow rate, and the applied voltage. The membrane played a role in promoting hydrogen production by inhibition of the reverse reaction from hydrogen to ammonia, while the plasma was increased the hydrogen permeation flux. To more increase the hydrogen permeation flux, a catalytic reactor for ammonia cracking was connected to the plasma membrane reactor. The current hydrogen production system attained to the hydrogen production of 187 L/h and the energy efficiency of 47.9%.
Direct converting of methane has been investigated to using a reactor combining of catalyst and microwave heating.T he catalyst was mainly composed with two ways function,t hat one is Ni-HZSM-5-Mo2C physically mixed component as am ethane conversion,t he other is SiC as a microwave absorber. The “key element” is Ni-CNO (Ni-carbon-nano-onion), which is generated with procedure in methane decomposition, enable to bring about high catalytic activity and durability. In addition, Mg-adding Ni catalyst was showed higher activity under the low-MW irradiation condition.
We have developed high performance electrodes for reversible solid oxide cells (SOCs), which can operate as solid oxide electrolysis cells (SOECs) for efficient hydrogen production and solid oxide fuel cells (SOFCs) for efficient power generation. Double-layer hydrogen electrodes, consisting of a mixed conducting SDC with highly dispersed Ni-Co catalysts as the catalyst layer and a thin Ni-SDC or Ni—YSZ cermet as the current collecting layer exhibited very high performance at 750 to 800°C. We have succeeded in enhancing the performances and durability of LSCF-SDC composite oxygen electrodes by the use of a dense SDC interlayer with uniform thickness.
A novel water electrolysis system for hydrogen production using a Mn02 intermediate electrode with a 3D particle metal hydride(MH) negative electrode and a positive electrode is proposed, which consists of two-step electrochemical cycle for hydrogen and oxygen evolution. This water-splitting electrochemical cycle can achieve a high energy conversion efficiency during hydrogen production by increasing reaction surface area and reducing the ohmic overpotential between the electrodes through use of a thinner separator than that used in conventional systems. Furthermore, by supplying pulsed current instead of DC current this system can generate oxygen and hydrogen gases separately at different periods of time to disturb the formation of iron diffusion layers in the vicinity of the electrodes, reducing the overpotential caused by the diffusion layer drastically. The best electrolysis performance was recorded at a current density of 0.2 A cm-2, and the observed cell voltage was 1.69 Vat 25°C for a pulse frequency of 500 Hz, which is less than the corresponding conventional alkaline electrolysis.
Electrochemically anodized nano-crystalline silicon (nc-Si) layer is one of the self-organized Si nanostructures. In addition to efficient visible luminescence, many specific effects are induced in nc-Si. For instance, a multiple-tunneling electron transport through nc-Si dots interconnected with tunnel oxides leads to the emission of ballistic electrons. This electron emitter operates not only in vacuum but also in atmospheric pressure gases and even in solutions. Following summary on the emission mechanism and characteristics, it is shown here that the emitter acts as an active electrode supplying highly reducing electrons into solutions. No conventional electron emitters are available for this operation mode. In salt solutions, injected ballistic electrons promote reduction of positive ions and subsequent thin film deposition of metals and semiconductors. When driven in aqueous solutions such as water, acid, and alkaline solutions without counter electrodes, in addition, H2 gas is generated with no by-product like O2. Effects of energetic electron injection into water are investigated by voltammogram measurements. The H2 generation is associated with a pH value shift and an increase of H2 content. The mechanism of direct H2 generation is discussed in relation to the preferential reduction of H+ ions, including its technological potential.