A Solar to Chemical Strategy: Green Hydrogen as a Means, Not an End

Green hydrogen is the key to the chemical industry achieving net zero emissions. The chemical industry is responsible for almost 2% of all CO2 emissions, with half of it coming from the production of simple commodity chemicals, such as NH3, H2O2, methanol, and aniline. Despite electrolysis driven by renewable power sources emerging as the most promising way to supply all the green hydrogen required in the production chain of these chemicals, in this review, it is worth noting that the photocatalytic route may be underestimated and can hold a bright future for this topic. In fact, the production of H2 by photocatalysis still faces important challenges in terms of activity, engineering, and economic feasibility. However, photocatalytic systems can be tailored to directly convert sunlight and water (or other renewable proton sources) directly into chemicals, enabling a solar-to-chemical strategy. Here, a series of recent examples are presented, demonstrating that photocatalysis can be successfully employed to produce the most important commodity chemicals, especially on NH3, H2O2, and chemicals produced by reduction reactions. The replacement of fossil-derived H2 in the synthesis of these chemicals can be disruptive, essentially safeguarding the transition of the chemical industry to a low-carbon economy. As the chemical industry seeks to achieve net-zero emissions, green hydrogen emerges as a critical solution. This work explores the potential of photocatalysis in the production of essential commodity chemicals, such as NH3 and H2O2, driven by sunlight and water. While challenges remain, recent successes demonstrate the viability of this solar-to-chemical strategy, presenting a disruptive path toward a low-carbon economy and the decarbonization of the chemical industry.image

Automated summary

Green hydrogen is crucial for achieving net zero emissions in the chemical industry. Photocatalysis shows great potential in producing essential commodity chemicals, driven by sunlight and water.