Catalytic Performance and Near-Surface X-ray Characterization ofTitanium Hydride Electrodes for the Electrochemical NitrateReduction Reaction

The electrochemical nitrate reduction reaction (NO3RR) on titanium introduces significant surface reconstructionand forms titanium hydride (TiHx,0<= 2). Withex situgrazing-incidence X-ray diffraction (GIXRD) and X-ray absorptionspectroscopy (XAS), we demonstrated near-surface TiH2enrichment with increasing NO3RR applied potential and duration. Thisquantitative relationship facilitated electrochemical treatment of Ti to form TiH2/Ti electrodes for use in NO3RR, therebydecoupling hydride formation from NO3RR performance. A wide range of NO3RR activity and selectivity on TiH2/Ti electrodesbetween-0.4 and-1.0 VRHEwas observed and analyzed with density functional theory (DFT) calculations on TiH2(111). Thiswork underscores the importance of relating NO3RR performance with near-surface electrode structure to advance catalyst designand operation

Automated summary

The study demonstrates the surface reconstruction and formation of titanium hydride on titanium electrodes during the electrochemical nitrate reduction reaction. The obtained quantitative relationship allows the decoupling of hydride formation from the reaction performance, and enables the design and operation of catalysts for the NO3RR. The NO3RR activity and selectivity of TiH2/Ti electrodes at different potentials were analyzed using density functional theory calculations.