In a world with a demand higher than its available resources, the crisis of climate change & energy insecurity poses a great threat. Carbon dioxide (CO₂), often seen as a pollutant, may quickly become a valuable resource. Scientists around the world are developing methods to convert it into methane - a cleaner burning fuel - using catalytic processes. By integrating this technology into our daily lives, we could potentially reshape our energy future & successfully combat climate change.

Methanation:

This is the process of converting CO₂ into methane. It occurs with the presence of a catalyst when CO₂ reacts with hydrogen in the air. This leads to the production of methane which, when burnt, only releases water as a product and has a significant energy potential. Usually

this requires extremely high temperatures but the use of a catalyst has also reduced this,

making it more viable and efficient.

About Catalysts:

At their core, catalysts essentially increase rates of reactions, making them faster by reducing the activation energy of reactants and providing alternate reaction pathways. In methanation, the catalysts are made of advanced materials such as metal nanoparticles to selectively break the bonds in CO₂ molecules and allow them to form bonds with hydrogen. This enables the production of methane with high efficiency, minimising waste and maximising output. In this reaction photocatalysts are used.

Challenges and The Future :

While this solution holds promise, producing green hydrogen is a big challenge - it is costly and energy-intensive. Moreover, catalysts for big scale productions such as this requires further research before being able to be implemented. However, ongoing advancements suggest that this may not be an issue for the future. By incorporating this new solution with ones already in place (e.g. solar power) we can create a sustainable cycle that transforms harmful emissions into useful resources. Despite technological and financial constraints, the potential of this is not diminished.

Role of Light in Photocatalysts

Light particles (photons) are absorbed by photocatalysts and excite electrons so they move within their structure. This causes the electrons to move up an energy level, leaving behind a positively charged hole which is what drives redox reactions to take place. In methanation, electrons reduce CO₂ into intermediate compounds (e.g. COOH-) or methanol. The protons also often form water or other hydrogen sources which combine with these intermediates to form methane, the desired product.

Structure of Photocatalysts

• Semiconductor metals: these materials are widely used because they have band gaps which can get activated by visible light or sunlight via the photons. 

• Metallic co-catalysts: these enhance the catalyst’s ability of transferring electrons, improving the overall efficiency of this reaction.

• Surface modifications: modifying the surface by adding additional functional groups or altering the surface allows more CO₂ molecules to be trapped.

Ways To Enhance Photocatalysts

• Doping: this involves adding elements, mostly transition metals, to further reduce the activation energy required to start the reaction.

• Plasmonic nanoparticles: adding metals like gold & silver can amplify light absorption.

• Heterojunction designs: combining different semiconductors (e.g. TiO2 with g-C3N4) helps

• optimize electron-hole separation therefore increasing the catalyst’s efficiency.