HyperSolar reaches 1.25 V for water-splitting with its self-contained low-cost photoelectrochemical nanosystem

10 December 2014

HyperSolar, Inc. announced that it had reached 1.25 volts (V) of water-splitting voltage with its novel low-cost electrolysis technology. Future development efforts will focus on increasing the currents and photovoltages beyond 1.5V.

The theoretical minimum voltage needed to split water molecules into hydrogen and oxygen is 1.23 V (at 25 °C at pH 0). However, in real world systems, 1.5 V or more is generally needed because of the low reaction kinetics. So far, other researchers have mainly achieved this voltage level through the use of either inefficient materials, such as titanium oxide, or very expensive semiconductors, such as gallium arsenide, HyperSolar noted. Further, overcoming the corrosive degradation of these “artificial photosynthesis” systems remains a challenge and has thus far eluded commercialization.

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HyperSolar’s research is centered on developing a low-cost and submersible hydrogen production particle that can split water molecules using sunlight, emulating the core functions of photosynthesis. Each particle is a complete hydrogen generator that contains a novel high voltage solar cell bonded to chemical catalysts by a proprietary encapsulation coating.

Hypersolar’s technology has two main features:

• Self-contained Photoelectrochemical Nanosystem. The low-cost nano-size particle technology is designed to mimic photosynthesis and contains a solar absorber that generates electrons from sunlight, as well as integrated cathode and anode areas to readily split water and transfer those electrons to the molecular bonds of hydrogen.
  

  
  Nanosystem for water electrolysis. Click to enlarge.

  Unlike solar panels or wind turbines that produce a sizeable number of electrons that will be lost before reaching the hydrogen bonds, the nanoparticles are optimized to ensure maximal electron generation and utilization efficiency, the company claims. Consequently, the nanoparticle technology uses substantially fewer expensive photovoltaic elements than conventional solar panels to achieve the same system level efficiency. This lowers the system cost of what is essentially an electrolysis process.

• Protective Coating. The biggest problem with submerging photovoltaic elements in water for direct electrolysis is corrosion and short circuiting. To address this problem, HyperSolar developed a protective coating that encapsulates key elements of the nanoparticle to allow it to function for a long periods of time in a wide range of water conditions without corrosion. This allows the nanoparticles to be submerged or dissolved into virtually any source of water, such as sea water, runoff water, river water, or waste water, instead of purified distilled water.

In October, HyperSolar reported the development of a novel reactor design and system architecture that circumvents the need for an oxygen-hydrogen separation process. Self-contained sunlight-driven water-splitting technology—“artificial photosynthesis”—typically produces hydrogen and oxygen gas bubbles in the same reactor. This hydrogen-oxygen gas mixture is potentially explosive and must be quickly separated. Current gas separation technology uses selective membranes and is very expensive and the membranes need to frequently replaced.

HyperSolar’s system uses a high voltage solar cell, wrapped in the company’s patent pending polymer coating, that serves two functions: (1) converts sunlight into electricity to split water into hydrogen on one side, and oxygen on the other side, and (2) acts as a physical barrier preventing oxygen from combining with hydrogen. The respective hydrogen and oxygen gas bubbles to the top of the reactor as two separate and pure gas streams.

Our teams at the University of California, Santa Barbara and at the University of Iowa have been working diligently to achieve efficient renewable hydrogen production. Our low cost, submersible semiconductor technology does not require a fossil fuel component, making the process truly as ‘green’ as possible. We are pleased that this milestone brings us one step closer to producing hydrogen fuel at or near the point of distribution, and at a cost reasonable enough to ensure industrial scalability.