Photo-assisted electrochemical CO2 reduction at a boron-doped diamond cathode

Goki Iwai, Andrea Fiorani, Jinglun Du, Yasuaki Einaga

Research output: Contribution to journalArticlepeer-review


We report on the coupling of photoelectrochemical water oxidation and electrochemical CO2 reduction to formic acid for a photoelectrochemical system capable of light and electrochemical energy conversion to chemical energy. Titanium oxide nanotubes (TiO2 NT) and boron-doped diamond (BDD) electrodes were used as a photoanode and a cathode, respectively. From CO2 electrochemical reduction at BDD, formic acid was obtained with a faradaic efficiency of about 86% and the system provided an overall energy conversion efficiency of 5.5%. From previous CO2 reduction at a dark electrolyzer based on a BDD cathode, the cell voltage was reduced from 2.7 V to 1.4 V with 52% saving of the electrical energy input. This resulted in an increase from 50% to nearly 80% of electrical-to-chemical energy conversion efficiency.

Original languageEnglish
JournalEnergy Advances
Publication statusAccepted/In press - 2023

ASJC Scopus subject areas

  • Energy (miscellaneous)
  • Energy Engineering and Power Technology
  • Fuel Technology
  • Renewable Energy, Sustainability and the Environment


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