Tethering Cobalt Ions to BiVO4 Surface via Robust Organic Bifunctional Linker for Efficient Photoelectrochemical Water Splitting

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-11, Vol.20 (48), p.e2403336-n/a
• Main Authors: Jahangir, Tahir Naveed, Ahmed, Tauqir, Ullah, Nisar, Kandiel, Tarek A.
• Format: Article
• Language: English
• Subjects: 3‐(bis(pyridin‐2‐ylmethyl)amino)propanoic acid (DPAA); Alanine; Anodizing; bifunctional linker; Bismuth oxides; BiVO4; Catalysts; Charge efficiency; Charge transfer; Cobalt; Efficiency; functionalized photoanode; molecular oxygen evolution catalysts; Oxidation; Oxygen evolution reactions; Photoanodes; Photoelectric effect; Propionic acid; Robustness; Tethering; Vanadates; Water splitting
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202403336

In the quest for efficient and stable oxygen evolution catalysts (OECs) for photoelectrochemical water splitting, the surface modification of BiVO4 is a crucial step. In this study, a novel and robust OEC, based on 3‐(bis(pyridin‐2‐ylmethyl) amino) propanoic acid bifunctional linker known as dipicolyl alanine acid (DPAA) and cobalt ions, is prepared and fully characterized. The DPAA is anchored to the surface of BiVO4 and utilized to tether cobalt ions. The Co‐DPAA/BiVO4 photoanode exhibits remarkable stability and efficiency toward photoelectrochemical water oxidation. Specifically, it showed anodic photocurrent increase of 7.1, 5.0, 3.0, and 1.3‐fold at 1.23 VRHE as compared to pristine BiVO4, DPAA/BiVO4, Co‐BiVO4, and Co‐Pi/BiVO4 photoanodes, respectively. The photoelectrochemical and IMPS studies revealed that the Co‐DPAA/BiVO4 photoanode exhibits a longer transient decay time for surface‐trapped holes, higher charge transfer kinetics, and charge separation efficiency compared to Co‐Pi/BiVO4 and pristine BiVO4 photoelectrodes. This indicates that the Co‐DPAA effectively reduces surface recombination and facilitates charge transfer. Moreover, at 1.23 VRHE, the Co‐DPAA/BiVO4 photoanode achieved a faradic efficiency of 92% for oxygen evolution reaction and could retain a turnover frequency of 3.65 s−1. The exhibited efficiency is higher than most of the efficient molecular oxygen evolution catalysts based on Ru. In this study, a novel and robust 3‐(bis(pyridin‐2‐ylmethyl) amino) propanoic acid bifunctional linker, known as dipicolyl alanine acid (DPAA), is used to tether cobalt ions onto the surface of BiVO4. The Co‐DPAA/BiVO4 photoanode showed outstanding stability and photoelectrochemical efficiency. At 1.23 VRHE, it achieved a faradic efficiency of 92% for oxygen evolution reaction (OER) and unprecedented turnover number (101,198.0) and turnover frequency (3.65 s−1).