Hydrogen Evolution Apparatus Using AC Power and Heterojunction Electrodes
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Solution Overview
Problem
Existing hydrogen evolution apparatuses face challenges in consistently producing hydrogen due to corrosion and reduced efficiency when using DC power sources, as they require conversion of AC power to DC, leading to electrode corrosion and increased voltage needs.
Innovation Solution
A hydrogen evolution apparatus utilizing an AC power source with a semiconductor electrode having a three-dimensional heterojunction structure, composed of alternately disposed n-type and p-type semiconductors, which suppresses charge recoupling and electrical double layer formation, allowing for efficient hydrogen production without the need for DC conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a DC power source is used in the hydrogen evolution apparatus, then hydrogen can be produced through electrochemical reactions, but the electrode undergoes corrosion due to continuous accumulation of photo charges, degrading the apparatus efficiency over time
Solution Approach 1:
The patent applies periodic action by using AC power source instead of DC power source. The alternating current periodically reverses the polarity of the electrode, preventing continuous accumulation of photo charges that cause corrosion. This periodic reversal of electrical polarity allows the electrode to alternately undergo reduction and oxidation processes, eliminating the one-directional charge accumulation that occurs with DC power sources and thereby maintaining electrode durability while sustaining hydrogen production.
Solution Approach 2:
The patent changes the electrical parameter from direct current (DC) to alternating current (AC). This parameter change fundamentally alters the behavior of photo charge accumulation on the electrode. By switching from a unidirectional current that continuously drives charges in one direction to a bidirectional current that periodically reverses direction, the system prevents charge accumulation and its associated corrosion effects, thus resolving the contradiction between maintaining productivity and ensuring reliability.
2Productivity
If a DC power source is used, then hydrogen evolution can proceed, but additional equipment for AC to DC conversion is required, increasing device complexity
Solution Approach 1:
The patent applies inversion by reversing the conventional approach. Instead of converting AC power to DC power as is traditionally done, the invention directly uses AC power source without any conversion equipment. This inverted approach eliminates the need for complex rectifier circuits, capacitors, and control systems that would otherwise be required for AC-DC conversion, thereby significantly simplifying the device while maintaining hydrogen production capability.
Solution Approach 2:
The patent extracts and removes the AC-DC conversion subsystem from the hydrogen evolution apparatus. By taking out the rectifier, filter capacitor, and associated control circuitry that would be necessary for DC power supply, the design directly connects the AC power source to the electrochemical cell. This extraction eliminates the source of complexity while preserving the essential hydrogen production function through direct AC-driven electrochemical reactions.
3Power
If DC power is continuously applied to the light absorbing layer, then electrochemical reactions can occur, but photo charge accumulation causes corrosion and limits photo charge producing efficiency
Solution Approach 1:
The patent employs periodic action through AC power application, where the electrical polarity is continuously reversed. This periodic reversal prevents the continuous accumulation of photo charges in the light absorbing layer. During each half-cycle, charges are generated and utilized for electrochemical reactions, but before significant accumulation can occur, the polarity reverses, clearing the accumulated charges. This cyclic process maintains high photo charge producing efficiency while sustaining the power necessary for electrochemical reactions.
Solution Approach 2:
The patent changes the electrical parameter from constant DC voltage to time-varying AC voltage. This parameter change transforms the photo charge generation and utilization dynamics. Instead of continuous unidirectional charge accumulation under DC, the AC parameter creates oscillating charge generation and consumption, preventing saturation and maintaining high efficiency in photo charge production while providing sufficient power for sustained electrochemical reactions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The AC power source system reduces the voltage required for hydrogen production, minimizes electrode corrosion, and enhances charge transport efficiency, enabling eco-friendly hydrogen generation with reduced energy consumption and expanded applicability to produce both hydrogen and oxygen.
Implementation Method 1
a light source which irradiates light on the semiconductor electrode
Implementation Method 2
electrons of the electrode react with H+ ions in the water to produce hydrogen
Data Source
AI summary
The present disclosure relates to a hydrogen evolution apparatus including an AC power source, a semiconductor electrode and a counter electrode connected to the AC power source, an electrolyte in which the semiconductor electrode is immersed, and a light source which irradiates light on the semiconductor electrode, in which the semiconductor electrode includes a conductive substrate and n-type semiconductor particles dispersed on a p-type semiconductor matrix or p-type semiconductor particles dispersed on an n-type semiconductor matrix which is vertically grown from the conductive substrate.