Driven by solar power and derived electricity, ambient photo‐ and electrochemical nitrogen fixations are considered promising strategies to produce low‐concentration NH3/NH4+. Under the principles of doping and interface engineering, a Ag/PW12/Zr‐mTiO2 composite is fabricated in a one‐pot synthesis, where zirconium‐doped mesoporous TiO2 is co‐decorated with silver nanoparticles (Ag NPs, optimal 1 wt%) and phosphotungstic acid (PW12, optimal 10 wt%). Enhanced nitrogen chemisorption is achieved owing to Zr‐doping, where the mesoporous structure of Zr‐mTiO2 favors nitrogen mass transfer. Ag NPs decoration leads to visible light absorption. At the interface, PW12 and Ag NPs decelerate the recombination of photo‐generated charge carriers. A Z‐scheme mechanism is suggested for the hetero‐junction, and the surface plasmon resonance effect of Ag NPs is considered in the composite. Consequently, a NH3/NH4+ production rate of 324.2 µmol gcat−1 h−1 is achieved in the photo‐driven process, together with the structure‐reactivity relationship between transient photocurrent intensity and catalytic efficiency. Moreover, constructing Ag/PW12/Zr‐mTiO2 heterojunction introduces a plentitude of active sites for the electrochemical process, together with enhanced charge transfer efficiency at the interface. Hence, an excellent NH3/NH4+ production rate of 55.0 µg mgcat−1 h−1 is accomplished at −0.6 V vs RHE. The robustness and superior activity of Ag/PW12/Zr‐mTiO2 in both photo‐ and electro‐driven processes may offer an opportunity for effectively utilizing sunlight.
Advanced Sustainable Systems – Wiley
Published: Oct 20, 2021
Keywords: electrocatalysis; heterojunctions; nitrogen fixation; photocatalysis; polyoxometalates