This would impact their catalytic behaviors, such as Brønsted acidity or deactivating Pt/Al2O3, leading to the varying results among the three TiO2. We also note that three batches of TiO2-A-SG were synthesized for this work, which all exhibit hydrocracking activity with Ni, but the rate varies to a minor extent (two batches shown in Table , the third batch between them). This could be due to the subtle structural difference among the batches in surface area, exposed facets, and/or defects. This novel discovery invokes complicated questions on the structure and property of the carboxylate layers and BAS on TiO2, which are fundamentally intriguing and practically appealing as they can serve as a new type of Brønsted-acid catalysts under proper conditions for reactions beyond polyolefin hydrocracking. While this work focuses on polyolefin upcycling over M/TiO2-A-SG, we will attempt to address these questions with more detailed spectroscopic studies and simpler probe reactions in the future.