Direct Z‐scheme among Niobium Pentoxide and Poly(heptazine imide) for NH3 Photoelectrosynthesis under Ambient Conditions

Abstract There is a crescent need to improve well‐known processes to environmentally friendly options, and NH 3 production is not an exception. Herein, we describe the photoelectrochemical nitrogen reduction reaction under a carbon nitride, the poly(heptazine imide) (PHI) using mild conditions for NH 3 synthesis. For this purpose, PHI was combined with Nb 2 O 5 nanotubes, leading to a new photocathode with a charge transfer process in a Z‐scheme structure. The photoelectrocatalytic N 2 reduction was carried out in Nb 2 O 5 Nt/PHI using solar‐simulated radiation and with an applied bias of −0.3 V Ag/AgCl . The PHI presence in the photocathode showed not only superior stability compared to bare Nb 2 O 5 , but also an ammonia generation rate of 0.156 mmol L −1 h −1 cm −2 , which is about 10‐fold higher than the amount obtained with niobium oxide alone. The mild and green conditions employed for ammonia generation place the obtained photocathode as a promising option for the currently used Haber‐Bosch process.