### 1. Introduction

^{2}. Corrosion on the electrode surface and bad contacts during conduction affect the efficiency of the electrolyser, but heat generated by ohm impedance causes a heating reaction at the interface during the electrolysis process, which could promote the occurrence of electrochemical reactions to a certain degree [6]. The addition of even more could make the whole electrolyser spin at a constant high velocity. The centrifugal force would lower the overpotential and improve efficiency, thus the improvement of efficiency due to the spinning of the whole electrolyser could make up for the energy loss [7]. However, there has been relatively little research articles aimed at reducing energy loss. Increasing the operating temperature from 30°C to 90°C could increase the efficiency of hydrogen production [8], while increasing the operating pressure to 70 bar and considering the ohm impedance effect on the electrolyser is found to increase the pressure which also increases the efficiency of hydrogen production in both experiment and theory [9]. Furthermore, there have been some improvements obtained by finding the optimal parameters, conditions for performance operation and energy efficiency for the electrolyser. Experiments have been carried out by using heated water cycles and electrode currents with two acid electrolytes, hydrogen bromide and sulfuric acid [10], or by using IrxRuyTazO

_{2}electrodes, and changing the ratio between Ta and Ru [11].

### 2. Experimental

### 2.1 Materials and Methods

#### 2.1.1 Electrolysis of Water

_{2}O) into oxygen (O

_{2}) and hydrogen gas (H

_{2}) due to an electric current being passed through the water. The parameters studied include the pressure, temperature and concentration of the electrolyte. In this study, the effects of differences in electrolyte concentration in a PEM electrolyser are discussed. Discussion of electrolysis is divided into two parts, because there are two kinds of electrolyte, acidic and alkaline. The acidic electrolytic chemical equations are as follows:

#### 2.1.2 Electrolyser Design

*I*is the current (A),

*A*is the surface area of the electrode (cm

^{2}),

*x*is the distance between the electrodes (cm), Δ

*Φ*is the difference in the solution potential between the electrodes (V), and

*κ*is the ratio constant.

*κ*can also be called the conductivity and expresses the characteristics of the current passing easily through in the electrolyte solution. When the distance between cathode and the anode is smaller, the current due to electrolysis is larger, given the same electrode, electrolyte solution, and potential. Therefore, electrodes with a large surface area and a small distance between them become part of the overall design of the electrolyser.

#### 2.1.3 Diffusion Effect

*J*is the “diffusion flux”,

*J*measures the amount of substance that will flow through a small area during a small time interval (

*mol/m*

^{2}

*s*),

*D*is the diffusion coefficient or diffusivity in dimensions (

*m*

^{2}/

*s*),

*ϕ*is the concentration in dimensions (

*mol/m*

^{3}), and

*x*is the position (

*m*). The negative sign indicates that

*J*moves in the opposite direction with the gradient.

### 2.2 Experiments

#### 2.2.1 Experimental Devices

#### 2.2.2 Hydrogen Production

### 3. Results and Discussion

### 3.1 Effects of Hydrogen ions

### 3.2 Effects of Hydroxide ions

### 3.3 Effects of Impedance

### 3.4 Transport Phenomena

*C*is the concentration ratio,

_{R}*C*is the concentration of electrolyte at the anode side,

_{a}*C*is the concentration of electrolyte at the cathode side,

_{c}*I*is the response current ratio,

_{R}*I*is the response current for the corresponding concentration

_{c}*C*, and

_{c}*I*is the response current for the corresponding concentration

_{a}*C*.

_{a}*C*) is higher than 1, the response current ratio (

_{R}*I*) also becomes higher than 1. This means that when the concentration of the anode side is higher than the cathode side, the hydrogen ions passing through the exchange membrane tend to increase. So the diffusion flux becomes larger when the difference of concentration becomes higher, conforming to equation (7).

_{R}### 4. Conclusions

_{2}SO

_{4}at the anode channel and with 20 wt% at the cathode channel. In addition, increasing the difference in concentration of the sulfuric acid had an effect on the diffusion.