Method for forming methanol and formic acid

A method of forming formic acid, comprising:

• irradiating a mixture comprising water, carbon dioxide, carbon absorbent, and a photocatalyst, with visible light and UV light to reduce the carbon dioxide and form formic acid,
• wherein the photocatalyst comprises zinc oxide and manganese oxide,
• further comprising one or more of:
• the method is carried out at ambient temperature or ambient pressure, or both ambient temperature and ambient pressure;
• the photocatalyst comprises zinc oxide and manganese oxide has an octahedral framework such as cryptomelane such as OMS-2;
• the carbon absorbent is at least one of an amine or oxide;
• the carbon absorbent is selected from the group comprising:
• triethylamine, dimethylformamide, calcium oxide, and any mixture thereof;
• the volume ratio of the carbon absorbent to water is greater than 1:1;
• the volume ratio of the carbon absorbent to water is greater than 3:1;
• the carbon absorbent is a mixture of trimethylamine and dimethylformamide, and wherein the volume ratio of the carbon absorbent to water is 4:1;
• the weight ratio of zinc oxide to manganese oxide in the photocatalyst is in the range 50:1 to 1:50;
• the weight ratio of zinc oxide to manganese oxide in the photocatalyst is in the range 10:1 to 1:10;
• the weight ratio of zinc oxide to manganese oxide in the photocatalyst is in the range 3:1 to 5:1;
• wherein the UV light has a wavelength in the range of 350-400 nm;
• the visible light has a wavelength in the range of 600 nm to 800 nm;
• the irradiation is provided by direct sunlight;
• the method further comprises the steps of passing the carbon dioxide through the water and carbon absorbent to provide a wholly or substantially saturated solution;
• and passing the saturated solution across the photocatalyst;
• the method further comprises the step of separating the methanol from the water and the carbon absorbent;
• and/or
• the method further comprises the step of recycling the water and the carbon absorbent for further carbon dioxide absorption.