Abstract
Energy recycling and production using abundant atmospheric CO2 and H2O have increasingly attracted attention for solving energy and environmental problems. Herein, Pt-loaded Ti sheets were prepared by sputter-deposition and Pt4+-reduction methods, and their catalytic activities on both photocatalytic CO2 reduction and electrochemical hydrogen evolution were fully demonstrated. The surface chemical states were completely examined by X-ray photoelectron spectroscopy before and after CO2 reduction. Gas chromatography confirmed that CO, CH4, and CH3OH were commonly produced as CO2 reduction products with total yields up to 87.3, 26.9, and 88.0 μmol/mol, respectively for 700 °C-annealed Ti under UVC irradiation for 13 h. Pt-loading commonly negated the CO2 reduction yields, but CH4 selectivity was increased. Electrochemical hydrogen evolution reaction (HER) activity showed the highest activity for sputter-deposited Pt on 400 °C-annealed Ti with a HER current density of 10.5 mA/cm2 at −0.5 V (vs. Ag/AgCl). The activities of CO2 reduction and HER were found to be significantly dependent on both the nature of Ti support and the oxidation states (0,II,IV) of overlayer Pt. The present result could provide valuable information for designing efficient Pt/Ti-based CO2 recycle photocatalysts and electrochemical hydrogen production catalysts.
Highlights
Recycle energy production using abundant CO2 and H2O has been a challenging project for energy and environment solutions
The surface morphology was found to be mainly determined by thermal treatment temperature and the Pt-prepared conditions
Pt NPs and sputtered-Pt were loaded on Ti sheets with different oxidation states, and tested for photocatalytic CO2 reduction in a closed reaction chamber and electrochemical hydrogen evolution reaction
Summary
Recycle energy production using abundant CO2 and H2O has been a challenging project for energy and environment solutions. Fang et al prepared Pt-loaded TiO2 spheres (>500 μm) by a modified TiO2 sol-gel method and microwave-assisted Pt reduction method using ethylene glycol as the reducing agent [19] They reported CO2 reduction yields of CO and CH4 with 18 and 3.5 μmol g−1 h−1, respectively. Wang et al prepared ultrafine Pt (0.5–1 nm)/TiO2 nanostructures on ITO via aerosol chemical vapor deposition for TiO2 and gas-phase sputtering deposition for Pt NPs [22] They reported CO2 photoreduction efficiency of 1361 μmol g−1 h−1 for CH4 formation and 200 μmol g−1 h−1 for CO formation. Kometani et al tested CO2 reduction over Pt-loaded TiO2 under supercritical condition of water and CO2 at 400 ◦C and 30 MPa [23] They reported that CO (35.3 ppm), CH4 (42.7 ppm), and H2 (65.3 ppm) were major products, and HCOOH (1.7 μM) and HCHO (0.6 μM) were minor.
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