Porous TiWO₃/SrWO₄ with high titanium molar ratio for efficient photoelectrocatalytic nitrogen reduction under mild conditions

Ammonia synthesized by nitrogen reduction is the most promising new energy material. Photoelectrocatalytic (PEC) nitrogen reduction reaction (NRR) occurs under ambient conditions and is the optimal alternative to the energy-intensive Haber-Bosch method. Here, we report the one-step reaction synthesis of Ti-WO3/SrWO4 as a photocathode for ammonia synthesis. First-principles calculations demonstrate that Ti doping can afford nitrogen-adsorption sites, and Ti3+ undergoes chemical adsorption and becomes a nitrogen-activation site by providing electrons to nitrogen. Under light irradiation, the photogenerated electrons are captured by Ti4+; this is conducive to the activation and regeneration of Ti3+, thus forming a nitrogen fixation cycle and improving the nitrogen fixation yield. At -0.5 V vs. RHE, the ammonia synthesis efficiency reaches 11.17 mu g h(-1) cm(-2), which is four times that of SrWO4. Furthermore, the high stability and N-gas sensitivity of Ti-WO3/SrWO4 in the NRR indicate that it can be used as an efficient and stable photoelectrocatalyst for ammonia synthesis.