The filing trend in this dataset peaked at 74 records in 2019 and has declined toward single digits by the most recent partial year, with the 2022 midpoint of 44 confirming the drop is real rather than a data gap. This pattern is consistent with a field where core oxidation, reduction and dispersion methods were claimed early and heavily, leaving less unclaimed ground for new filings. It does not mean commercial interest in graphene oxide has stopped; it means the patent claim space for these specific methods has become more crowded, pushing new work toward adjacent applications like battery electrodes or laminates rather than the core chemistry itself.

China accounts for 346 of the 653 records in this corpus, more than the next four receiving offices combined (US at 130, EPO at 63, India at 32, WIPO at 28). Any competitive or freedom-to-operate analysis in this field needs to include Chinese-language filings, since excluding them would mean missing over half of the identified prior art. That said, the choice of where to file your own application should follow your target markets and manufacturing base, not just where prior art density is highest.

US9318231B2, held by Korea Institute of Science and Technology, claims a method of preparing reduced graphene oxide by covalently binding a halogen-substituted aromatic compound to graphene oxide and then heat-treating it at 450 degrees Celsius or less, producing reduced graphene oxide with electrical conductivity of 30,000 S/m or more. It is a process claim tied to a specific chemistry (halogen-substituted aromatic binding) and a specific low-temperature thermal treatment step, not a claim over reduced graphene oxide generally. Anyone using a different chemical route to bind functional groups before reduction, or a different heat-treatment regime, is working outside its literal claim scope, though a design-around should be checked against the full claim set, not the abstract alone.