The Ratio of <i>sp</i> <sup>2</sup> and <i>sp</i> <sup>3</sup> Hybridized Carbon Determines the Performance of Carbon‐based Catalysts in H <sub>2</sub> O <sub>2</sub> Electrosynthesis from O <sub>2</sub>
Dayu Zhu, Hsiwen Wu, Wye‐Khay Fong, Rico F. Tabor, Jie Zhang
Abstract
Abstract Introducing oxygen‐ or carbon‐containing functional groups is a widely adopted strategy to optimize the performance of carbon‐based catalysts for the two‐electron oxygen reduction reaction (2 e − ORR). Nevertheless, the specific contributions of these functional groups to enhance activity and selectivity are not well‐defined and continue under debate. In this study, we systematically modified carbon materials by controlling the contents of oxygen functional groups (OFGs) and carbon functional groups (CFGs). Surface compositions were accurately quantified using X‐ray photoelectron spectroscopy, and 2 e − ORR performance was evaluated using a rotating ring‐disk electrode (RRDE) in 0.1 M KOH. Through reliable statistical analyses, including partial least squares regression and linear regression, we explored the correlations between the surface compositional features – specifically the ratios of OFGs, CFGs, and sp 2 / sp 3 hybridized carbon – and the catalytic performance metrics such as onset potential and H 2 O 2 selectivity. Our findings challenge existing paradigms by demonstrating that the sp 2 / sp 3 ratio is a critical factor in determining catalytic selectivity and a certain correlate with the 2 e − ORR onset potential. By tuning this ratio, we achieved nearly 100 % H 2 O 2 selectivity within 0.4–0.6 V vs. RHE, and onset potential approached the thermodynamic potential (0.766 V vs. RHE for the O 2 /HO 2 ‐ process), pointing a new direction in designing and developing advanced electrocatalysts for sustainable H 2 O 2 synthesis.