Periodic Reporting for period 2 - Sun-To-X (Solar Energy for Carbon-Free Liquid Fuel)
Période du rapport: 2022-03-01 au 2023-02-28
Currently around 80% of the energy we use comes from chemical fuels, such as gasoline. Although renewable energy sources are increasingly used for electricity generation, the production of chemical fuels has proven more challenging. However, we urgently need to address this problem to achieve the goals set by the European Commission to be carbon neutral by 2050. The Sun-To-X project aims to develop technology for the production of chemical fuels derived from solar energy. In the first step of our process, we will use solar energy to produce hydrogen from water (from ambient humidity or rain) through a photoelectrochemical device. In the second step, the hydrogen will be reacted with a silicon oxide precursor to form HydroSil - a energy dense, non-toxic, liquid fuel, which can utilise existing infrastructure for its transport to consumers. When used in combination with a fuel cell, Hydrosil produces only water as an output, along with the silicon oxide starting material which can be recharged with hydrogen. In the scope of the project, we will also explore another use for Hydrosil in the recycling of waste plastics. The Si-H bonds in Hydrosil can react with plastics to form hydrocarbon materials.
Solar Hydrogen Production:
A transparent conducting porous substrate has been developed as a photoelectrode support - this substrate allows gas (humidity) to enter the photoelectrode whilst allowing light to pass through the photoanode (on top of the device - absorbing blue - green light) to photocathode (absorbing red light). The most suitable semiconducting material for photocathode has been selected – an organic, conducting polymer. For the photoanode, an inorganic oxide has been selected. In order to capture water and bring it in contact with the photoelectrode, functionalisation with water absorbing materials is being developed and with photoelectrode functionalization we have been able to achieve in the levels of > 90% performance in vapor phase operation (80% relative humidity) vs liquid one for short timescales. Efforts are now directed to improve stability over longer timescales. We have constructed a 100 cm2 prototype and testing in the prototype is now on-going.
Silicon Hydrides and their Use for Recyling of Plastics:
The different reaction steps for storing hydrogen in HydroSil and the connection between them have been validated and a reactor has been designed. Techniques to characterise the silicon hydride materials have also been developed. Catalysts have been tested to enhance the reaction of the Si-H bonds in HydroSil for the breakdown of waste plastics. With an optimised catalyst, more than 95% conversion of waste plastics to hydrocarbon materials has been achieved.
Communication and Dissemination
Sun-To-X has engaged with stakeholders through attendance of workshops and conferences, publications and social media. Particularly the transparent photoelectrode support has generated a lot of interest in the media.
A transparent conducting porous substrate has been developed as a photoelectrode support - this substrate allows gas (humidity) to enter the photoelectrode whilst allowing light to pass through the photoanode (on top of the device - absorbing blue - green light) to photocathode (absorbing red light). The most suitable semiconducting material for photocathode has been selected – an organic, conducting polymer. For the photoanode, an inorganic oxide has been selected. In order to capture water and bring it in contact with the photoelectrode, functionalisation with water absorbing materials is being developed and with photoelectrode functionalization we have been able to achieve in the levels of > 90% performance in vapor phase operation (80% relative humidity) vs liquid one for short timescales. Efforts are now directed to improve stability over longer timescales. We have constructed a 100 cm2 prototype and testing in the prototype is now on-going.
Silicon Hydrides and their Use for Recyling of Plastics:
The different reaction steps for storing hydrogen in HydroSil and the connection between them have been validated and a reactor has been designed. Techniques to characterise the silicon hydride materials have also been developed. Catalysts have been tested to enhance the reaction of the Si-H bonds in HydroSil for the breakdown of waste plastics. With an optimised catalyst, more than 95% conversion of waste plastics to hydrocarbon materials has been achieved.
Communication and Dissemination
Sun-To-X has engaged with stakeholders through attendance of workshops and conferences, publications and social media. Particularly the transparent photoelectrode support has generated a lot of interest in the media.
Solar Hydrogen Production:
In Sun-To-X, we have focussed on the development of transparent gas diffusion electrodes and deposition of semiconductor materials onto these porous substrates which is a new concept for tandem device configurations. For this, we have developed techniques to deposit high performance semiconductors on porous supports. We have also developed a new type of porous support which is transparent (state-of-the-art supports are typically carbon or titanium, which don't allow light to pass through the photoanode to the photocathode) based on fluorine-doped tin oxide coated quartz felts. At the end of the project, we aim to have a 10% efficient solar-to-hydrogen device of around 1 m2. This photoelectrochemical device is expected to be a low cost solution for solar hydrogen production, as it is more integrated than the electrical connection of conventional photovoltaic panels to an electrolyser.
Hydrosil Synthesis and its Use for Recyling of Plastics:
We have demonstrated a complete process to store hydrogen in the form of HydroSil and examined how this can be effectively coupled to renewable energy sources. The HydroSil molecule has the advantage of being liquid at room temperature and pressure, like conventional fossil fuels, allowing us to make use of existing infrastructure for the transport and storage of this green fuel. The use of HydroSil in the recycling of waste plastics will allow the project to contribute to the development of a circular economy where waste can be valorised to useful products.
In Sun-To-X, we have focussed on the development of transparent gas diffusion electrodes and deposition of semiconductor materials onto these porous substrates which is a new concept for tandem device configurations. For this, we have developed techniques to deposit high performance semiconductors on porous supports. We have also developed a new type of porous support which is transparent (state-of-the-art supports are typically carbon or titanium, which don't allow light to pass through the photoanode to the photocathode) based on fluorine-doped tin oxide coated quartz felts. At the end of the project, we aim to have a 10% efficient solar-to-hydrogen device of around 1 m2. This photoelectrochemical device is expected to be a low cost solution for solar hydrogen production, as it is more integrated than the electrical connection of conventional photovoltaic panels to an electrolyser.
Hydrosil Synthesis and its Use for Recyling of Plastics:
We have demonstrated a complete process to store hydrogen in the form of HydroSil and examined how this can be effectively coupled to renewable energy sources. The HydroSil molecule has the advantage of being liquid at room temperature and pressure, like conventional fossil fuels, allowing us to make use of existing infrastructure for the transport and storage of this green fuel. The use of HydroSil in the recycling of waste plastics will allow the project to contribute to the development of a circular economy where waste can be valorised to useful products.