In the past ten years, photocatalysis has become very important both in technology and for the economy. These improvements are mostly thanks to advances in nanotechnology. We now use photocatalysis in many products, like things that don't fog up, self-cleaning surfaces, and devices that purify water and air, and even make hydrogen from sunlight. The market for photocatalyst products is expected to keep growing at a rate of about 12.6% each year for the next five years. By 2020, it could be worth nearly $2.9 billion. The construction sector is expected to make up a big part of that, around $2.6 billion. Products for regular consumers are also going to get bigger, going from $155.6 million in 2015 to $220.3 million in 2020, growing at a rate of about 7.2%. This means the market for environmental products is going to get a lot bigger."