The reaction with TEMPO helps confirm our suspicions that HAT/HSPE is the preferred mechanism, as both generate hydrogen radicals as the principal reducing agent. While the borophene layer does a great job of protecting the platinum atoms on the edges of the diboride single crystals, while doing this, it is calculated based on the Slater radii that the d-spacing between boron atoms is 1.578 Å. This spacing is what prohibits sulfur (2.0 Å) to adhere to platinum, this also contributes to strong interactions with hydrogen, allowing sufficient room for the hydrogen-platinum bond to form, followed by the dissociation of hydrogen atoms on the surface. Hydrogen, sticking out of the platinum 'pocket' has abundant room for reactions to occur, whether it be through HSPE or HAT mechanisms. In contrast, the catalyst displays a HAT-like mechanism in solution. It is generally accepted that for hydrogen spillover to occur, a nonreducible support must be present to allow the hydrogen spillover to occur. This coupled with doing the reactions in methanol solution suggests a more homogeneous catalyst-like mechanism.