Blocking the non-selective sites through surface plasmon-induced deposition of metal oxide on Au/TiO2 for CO-PROX reaction

Abstract

CO preferential oxidation (PROX) in excess hydrogen is a promising strategy for CO removal in hydrogen-rich reformate. However, the CO conversion and CO 2 selectivity in the PROX reaction dramatically decrease with rising temperature, resulting in a major challenge to complete CO removal across a wide temperature window. Here, we developed a photoexcited deposition of metal oxide (PDMO) method based on surface plasmonic resonance of Au nanoparticles, which can tune the interfacial properties by depositing lead oxide at the Au-TiO 2 interface. The interface modified Pb 3 O 4 /Au/TiO 2 catalyst can successfully eliminate CO in a wide temperature range (70°C–140°C) and exhibit superior stability in the PROX reaction. Further experiments demonstrated that the improved PROX performance is due to the severely depressed hydrogen oxidation through simultaneously inhibiting the activation of hydrogen and oxygen. The results further reveal that the interface of Au/TiO 2 is the superactive but non-selective site for H 2 and CO oxidation. • Photoexcited deposition of metal oxide method is employed for interface engineering • Interface-engineered Au-TiO 2 helps to identify the active site in CO and H 2 oxidation • Blocking the non-selective sites greatly improves the CO-PROX performance • Interface anchoring with inert lead oxide enhances long-term thermal stability Against the background of the carbon-neutral era, the liquid sunshine industry is booming due to the consumption of greenhouse gas (CO 2 ) and the solution of storage and transportation of H 2 energy. However, before the terminal application of H 2 energy, CO must be removed in the H 2 -rich reformate to avoid poisoning the noble metal catalysts. Gold-catalyzed CO preferential oxidation (PROX) has great potential in the removal of CO from H 2 -rich reformate. The competition oxidation of CO and H 2 at the interface of gold support always results in a decrease in CO oxidation conversion and selectivity, especially at high temperature. However, it is a major challenge to distinguish the interfacial sites from the other parts of nanoparticle surface. We show here that the interface of Au-TiO 2 is modified by our photoexcited deposition of metal oxide (PDMO) method, which greatly affects the performance of the CO-PROX reaction. The interfacial area of metal support is the ultrahigh active site in catalysis. However, the ultrahigh active sites are normally adverse for chemoselective oxidation or hydrogenation reaction. Interface-engineered catalyst is prepared based on a selective photoexcited deposition of metal oxide method and shows greatly improved performance in CO preferential oxidation in H 2 -rich stream (PROX reaction).