Two-stage thermal evolution of APPJ-deposited graphene oxide coatings on Cu

Graphene oxide (GO) coatings on Cu were deposited by atmospheric-pressure plasma jet (APPJ) and their thermal evolution in air (150–650 °C, 1 h) was mapped to define a practical process window for GO/Cu coatings in solar-absorber and thermally cycled applications. Air annealing produces a two-stage evolution: 150–250 °C increases defects through partial deoxygenation, whereas 350–450 °C reorganizes sp 2 domains and tends to stabilize or decrease I D /I G . Rough domains and delamination appear above ~450–500 °C, compromising coverage. Correlating Raman, reflectance, and microscopy identifies a 250–350 °C range that optimizes reduction while maintaining film integrity. Within this window, APPJ plus annealing enables tuning GO–Cu optical and structural properties in binder-free laminar coatings with minimal tooling. • APPJ enables binder-free self-assembly of uniform GO coatings on Cu. • Two-stage thermal response: 150–250 °C defects and 350–450 °C reorganization. • Processing window 250–350 °C balances reduction and coating integrity. • ≥450 °C induces roughness, coalescence, and CTE-driven delamination. • APPJ GO on Cu is a candidate solar-absorbing coating at 250–350 °C air annealing .