Steering methanol selectivity in plasma-assisted CO₂ hydrogenation via waveform control and CuZn/CeO₂ interface regulation

Non-thermal plasma (NTP) catalysis provides a promising route for CO₂ hydrogenation at room temperature and atmospheric pressure, avoiding the harsh conditions required in conventional thermocatalysis. Herein, the effect of discharge waveform on methanol formation over ZnCu/CeO₂ catalysts was investigated. Among the catalysts studied, Zn₁Cu₂/CeO₂ driven by sinusoidal AC plasma exhibited the best performance, achieving a CO₂ conversion of 8.38% and a methanol selectivity of 65.97%, together with reduced energy consumption. Structural characterizations indicate that an optimized Zn/Cu ratio promotes an oxygen-vacancy-rich surface environment and defect-enriched Cu/Zn-Ce interfacial structures, which are beneficial for CO₂ adsorption/activation and surface hydrogenation toward methanol. Under the investigated conditions, the discharge waveform strongly influences electron-energy characteristics, reactive species formation, and product distribution. AC plasma, with gradual voltage variation and relatively moderate electron-energy characteristics, is more favorable for mild CO₂ activation and surface-mediated methanol formation. In contrast, nanosecond pulsed plasma, with nanosecond-scale voltage rise and transient high-field events, tends to enhance gas-phase excitation, dissociation, ionization, and radical chemistry, leading to increased CO and hydrocarbon formation. These results suggest that product distribution in NTP-assisted CO₂ hydrogenation can be regulated by synergistically tuning catalyst interfacial structures and plasma discharge waveforms under mild conditions.