In good agreement with the prior report, conventional conditions employing Pt electrodes with direct current electrolysis led to no observable formation of 40 (Figure , entry 1), presumably due to electrode passivation (i.e. surface deterioration to block current from passing). Interestingly, the Kolbe reaction was previously studied with an AC waveform, and the detailed result was published in 1939 by Shipley and Rogers. In this report, no notable difference between DC and AC was observed on the reaction outcome, consistent with our findings that 40 was not formed in either case (entry 2). Altering the base, solvent as well as electrodes under DC electrolysis gave no improvement on the product formation (entries 3 and 4). Remarkably, simply switching the waveform from DC to rAP under the identical conditions of entry 4 led to formation of 40 in 63% isolated yield (entry 5). It is particularly surprising that Pt electrodes are not required under the rAP conditions, since Pt has, for over a century, been considered as essential for radicalbased Kolbe reactivity. In fact, carbon-based electrodes are known to promote carbocation reactivity instead, known as Hofer-Moest reaction. The unique effect of rAP to realize Kolbe reaction on carbon-based electrode (RVC) was found to be general. rAP generally gave comparable or higher yields than conventional Pt-based Kolbe system (41-43), and challenging substrates such as amino acids was also dimerized efficiently under the rAP conditions without epimerization (44). Kolbe reaction on amino acids is particularly useful when used in heterocoupling, as abundant glutamic or aspartic acid can be readily transformed into enantiopure high-value unnatural amino acids in a single step. For example, homologated glutamic acid 45, fluorinated norleucine 46 as well as subunit for paritaprevir 47 were obtained easily and inexpensively. Syntheses of these unnatural amino acids are not trivial via conventional synthetic logic. It is surprising that rAP-Kolbe (hetero)coupling works far beyond the canonical Kolbe scope under conditions that are seemingly opposite to what has been commonly recommended for over 100 years: carbon-based electrode in acetone rather than well-precedented Pt electrodes in protic solvent, and alternating polarity as opposed to the conventional DC. It stands in stark contrast to precedent 5 that suggests little effect of AC on Kolbe reaction. Accordingly, several key experiments were performed to understand how the rAP-Kolbe reaction operates. Surprisingly, the fundamental reactivity difference in the rAP-Kolbe reaction may stem, in a large part, from electrode local pH. In general, DC electrolysis creates local areas of enhanced acidity surrounding the anode at the microscopic level (regardless of stirring rate) through oxidation of solvent, water, or the substrate itself, known as electrogenerated acid. Counterintuitive to the fact that the reaction solution is partially neutralized, this phenomenon leads to protonation of carboxylate at the anode. As the direct oxidation of a carboxylic acid is extremely difficult, electrode passivation or oxidation of other functional groups outcompetes decarboxylative processes (that require a carboxylate). In contrast, rAP skirts this issue via fast polarity switching such that an anodic phase does not last long enough to create a persistent acidic electrode surface (due to rapid oscillation). Another contribution of pH buffering effect under rAP comes from acetone reduction, which occurs as a counter reaction and consumes two protons to generate isopropanol. As a result, oxidation of the deprotonated form (carboxylate) readily takes place on electrodes under rAP in preference to other functional groups. To support this hypothesis, a compound sensitive to acidic deprotection (50) was added in both DC-and rAP-Kolbe reactions (Figure ). DC electrolysis generated the parent alcohol 51 in 52% yield with the formation of Kolbe dimer 49 in 37% yield, whereas the probe 50 was almost intact under rAP conditions with much higher yield of 49. In addition to these experiments, a pH indicator (bromophenol blue) was added to the reaction solution to visualize pH environment. As expected, a low pH was detected around the anode during DC electrolysis, whereas no visible pH difference was observed under rAP. Another evidence for supporting electrode local pH difference was the product distribution dichotomy observed in the reaction of 38 (Figure ). While rAP-Kolbe reaction smoothly proceeded to furnish Kolbe dimer 54, DC electrolysis resulted in the formation of benzylic oxidation products 52 and 53 with no formation of 54 under the same reaction conditions. This dramatic product distribution change could also be rationalized by considering local acidity. Namely, a locally acidic anode in DC electrolysis prevents deprotonation of the carboxylic acid, which lead to arene oxidation (which resulted in benzylic oxidation products) instead of carboxylate. In contrast, 38 is oxidized as its deprotonated form under rAP, leading to selective decarboxylation without oxidizing the arene. The modulation of electrode pH is an overlooked phenomenon in synthetic organic electrochemistry that further illustrates the profound effect that altered waveforms can have on the course of a reaction. As briefly mentioned above, one of the most industrially promising applications of the Kolbe reaction involves the upconversion of biomass-derived chemicals into high-value chemicals for reducing our reliance on petroleum-based products. Thus far, reactions employed in this space are mostly simple functional group manipulations such as hydrogenation, condensation and elimination with exception of olefin cross metathesis for C-C bond formation. In this context, the Kolbe reaction has long been recognized as a potentially disruptive transformation since it forges saturated C-C bonds directly from carboxylic acids which are ubiquitous in biomassderived chemicals. No alternative reaction currently exists to form saturated C-C bond with this level of simplicity and sustainability. This exciting prospect, which has generated intense study in the area of sustainable synthesis, remains unanswered owing to the issue of extremely narrow reaction generality in classic Kolbe reaction.