Photoelectrocatalytic nitrogen fixation with Vo-BiOBr/TiO2 heterostructured photoelectrode as photocatalyst

Photocatalytic or photoelectrocatalytic nitrogen fixation is considered as a very promising way to reduce energy requirements. Here, V o -BiOBr/TiO 2 nanocomposite photoelectrode was constructed by modifying TiO 2 nanotube arrays with BiOBr nanosheets with oxygen vacancies (V o ) for photoelectrocatalytic nitrogen fixation. The oxygen vacancy promotes the adsorption and activation of N 2 on the catalyst surface. The Lewis basicity of nitrogen is enhanced by transferring the photogenerated electrons on the conduction band of BiOBr to the π anti-bonding orbit of N 2 , which is more beneficial for the addition of protons. On the other hand, the heterojunction between TiO 2 and V o -BiOBr facilitates the separation of photogenerated carriers. The photogenerated holes on the valence band of TiO 2 travelled to the counter electrode to produce oxygen at a negative potential, avoiding the further oxidation of NH 3 . V o -BiOBr/TiO 2 displays a high NH 3 production rate of 25.08 μg h −1 cm −2 at −0.2 V which is 3.3 times higher than that of BiOBr/TiO 2 . The synergistic effect between TiO 2 and V o -BiOBr results in enhanced light absorption and higher photoelectrocatalytic efficiency for the N 2 reduction reaction. Heterostructured V o -BiOBr/TiO 2 nanotube arrays shows remarkable NRR activity with an NH 3 yield of 25.08 μg h −1 cm −2 and the oxygen vacancies in BiOBr play an important role in promoting the N 2 adsorption and activation. • Heterostructured V o -BiOBr/TiO 2 nanotube arrays is constructed. • The oxygen vacancies in BiOBr promote the N 2 adsorption and activation. • The NH 3 production rate of 25.08 μg h −1 cm −2 is achieved over V o -BiOBr at −0.2 V. • V o -BiOBr/TiO 2 shows high photoelectrocatalytic fixation nitrogen stability.