Efficient photoelectrocatalytic conversion of CO2 to formic acid using Ag-TiO2 nanoparticles formed on the surface of nanoporous structured Ti foil

Global warming and adverse climate change, which have been intensified by a strident increase in carbon dioxide (CO2) emissions, have necessitated the development of alternative techniques to reduce the dis-proportionate concentration of CO2 in the atmosphere. The photoelectrochemical reduction of CO2 is a technique of lowering the energy required to convert greenhouse gases into useful end products. Herein, we have manufactured an innovative, cost-effective silver (Ag) decorated anatase TiO2 (TO-Agx; 'x' stands for different concentration of Ag) nanoparticles which created on the 3D nanoporous structured surface of a thin titanium foil (Ti-foil) by the assist of chemical treatment with hydrogen per-oxide (H2O2) and different concentrations (1, 5, 10, 20 mM) of silver nitrate (AgNO3) solution and fol-lowed by calcination at 500 degrees C. As-prepared samples were analyzed by several characterization techniques such as XRD, XPS, TEM and Raman spectroscopy. Among various samples (TO, TO-Ag1, TO-Ag5, TO-Ag20), the TO-Ag10 sample were exposed a supreme photocurrent density of 83.2 lA/cm-2 (86.1% higher than TO sample which is untreated with AgNO3 solution). Because of its high photocurrent density, the sample TO-Ag10 were selected as the electrode material for photoelectrochemical CO2 reduc-tion reaction and a lowest reduction onset potential (-1.018 V) was observed on linear sweep voltamme-try analysis in the presence of light with Ag/AgCl reference electrode. 1H NMR analysis of the product solution exposed the production of formic acid as a single product of CO2 reduction reaction after the chronoamperometric electrolysis were carried out more than 6 h. The maximum faradaic efficiency (73%) and formic acid yield (193 lmol cm-2 h-1) were found at an applied potential of-1.2 V (vs. Ag/AgCl reference electrode) for TO-Ag10 photocathode.(c) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

This study developed an innovative and cost-effective silver-decorated anatase TiO2 nanoparticle, which showed excellent performance in terms of photocurrent density and reduction onset potential for CO2 reduction reaction. This nanoparticle has the potential to be used in photoelectrochemical reduction of CO2 to alleviate global warming and adverse climate change.