Investigation of local structure modulation in CuO/WO3 heterojunction photocathode towards enhanced photoelectrochemical nitrate reduction t

The photo-electrochemical nitrate reduction reaction (PEC-NO3−RR) has two advantages: it contributes to the global nitrogen cycle back into balance and offers a less energy intensive method of producing ammonia. We have developed a CuO/WO3 heterojunction catalyst that gives a higher NH3 yield (1057 µg/h/mg) in the presence of visible light, which is 2.8-fold higher in comparison to the absence of light at the same applied potential (−1.4 V vs. Ag/AgCl). This means photoelectrons play a critical role in the nitrate reduction at CuO/WO3 heterojunction by influencing the CuO active sites. We propose to perform in-situ XANES to monitor Cu K and W L3-edge energies and EXAFS to understand shift in oxidation states and local coordination of the metal ions under applied potential in presence of 400 nm light. This study could help us to understand the role of photoelectron transfer at the heterojunction in enhancing the efficiency of nitrate reduction.