Platinum and palladium nanoparticles on boron-doped diamond for the electrochemical detection of hydrogen peroxide: a comparison study.

Hydrogen peroxide (HO) plays a role in many facets - a household item, an important industrial chemical, a biomarker in vivo, and several others. For this reason, its measurement and quantification in a variety of media are important. While spectroscopic detection is primarily used for HO, electrochemical methods offer advantages in versatility, cost, and sensitivity. In this work, we investigate a 2-step surface metal nanoparticle (NP) modification for platinum (Pt) and palladium (Pd) on boron-doped diamond (BDD) electrodes for the detection of HO. Several parameters such as the metal salt concentration and electrodeposition charge in the 2-step modification were varied to find an optimum. Using cyclic voltammetry (CV), the BDD-PdNP electrode types were found to yield a sharper, more well-resolved HO oxidation peak compared to the BDD-PtNP electrodes. Both metal NP electrode types significantly improved the response compared to the bare BDD electrode; a 150-200× improvement in sensitivity was observed across all modified electrode types. Calibration experiments were completed at both low and high concentration ranges in stagnant and flow-based solutions. The lowest limit of detection (LOD) obtained was 50 nM (5E-08 M) on a BDD-PdNP electrode modified with 1.0 mM PdCl to 5.0 mC in the wet chemical seeding and electrodeposition steps. 0.25 mM PdCl to 3.23 mC and 0.25 mM HPtCl to 3.23 mC also yielded a sufficient response for low-level HO, with LODs around 100 nM (1E-07 M). Overall, this work exemplifies the wide applicability of BDD and achieves sub-μM HO LODs with a non-enzymatic electrode material.