Enhanced performance of diamond electrodes with heavily N-doped surface nanolayers grown by CVD for high reduction current density

作者：Taro Yoshikawa, Akira Kaga, Kimiyoshi Ichikawa, Kan Hayashi, Tsubasa Matsumoto, Ryosuke Izumi, Mitsuru Ohno, Satoshi Yamasaki, Norio Tokuda, Hitoshi Asakawa · 发表于：Electrochimica Acta · 年份：2025 · DOI：10.1016/j.electacta.2025.146058 · 被引用次数：4 · 研究领域：Diamond and Carbon-based Materials Research、Semiconductor materials and devices、Graphene research and applications

The diamond electrode with a heavily N-doped surface nanolayer has the potential to revolutionize not only the production of CO from CO 2 reduction, but also the production of various chemicals using reduction reactions. However, the current density attributed to the reduction reaction remains insufficient for industrial requirements. In this study, we investigated the fundamental electrochemical behavior of diamond electrodes with heavily N-doped surface nanolayers through polarization curve measurements for hydrogen evolution reaction in the dark and upon visible-light irradiation. Two types of layers, a chemical vapor deposition (CVD)-processed diamond layer containing detonation-synthesized nanodiamonds (DNDs) and a heavily N-doped CVD-processed diamond (NDD) layer without DNDs, were used as heavily N-doped surface nanolayers and compared mainly in terms of the electron transfer coefficient and visible-light responsiveness. Electron transfer at the electrode surface for the DND-based layer was limited, whereas it was unrestricted for the NDD layer; however, the current density was suppressed in the larger negative-current-density region. Moreover, the NDD layer enabled a more effective conversion of visible-light energy to the photovoltaic effect than the DND-based layer. These results suggest that the electrode surface is better capped by less-defective diamond crystals, whereas the N-doped layer has sufficient conductivity to enable a larger reduction current density. S...