Photoassisted CO₂ methanation can be carried out efficiently at 250 °C using Cu₂O nanoparticles supported on few layer graphene (Cu₂O/G) as a photocatalyst. The Cu₂O/G photocatalyst has been prepared by chemical reduction of a Cu salt (Cu(NO₃)₂) with ethylene glycol in the presence of defective graphene obtained from the pyrolysis of alginic acid at 900 °C under Ar flow. Using this photocatalyst a maximum specific CH₄ formation rate of 14.93 mmol g_Cu2O⁻¹ h⁻¹ and an apparent quantum yield of 7.84% were achieved, which are among the highest reported values for the gas-phase methanation reaction at temperatures below the Sabatier reaction temperature (>350 °C). It was found that the most probable reaction mechanism involves photoinduced electron transfer from the Cu₂O/G photocatalyst to CO₂, while evidence indicates that light-induced local temperature increase and H₂ activation are negligible. The role of the temperature in the process has been studied, the available data suggesting that heating is needed to desorb the H₂O formed as the product during the methanation. The most probable reaction mechanism seems to follow a dissociative pathway involving detachment of oxygen atoms from CO₂.

中文翻译：

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使用负载在石墨烯上的Cu ₂ O纳米粒子作为光催化剂进行光辅助甲烷化

使用负载在几层石墨烯（Cu ₂ O / G）上的Cu ₂ O纳米粒子作为光催化剂，可以在250°C下有效地进行光辅助CO ₂甲烷化。Cu ₂ O / G光催化剂的制备方法是，在有缺陷的石墨烯存在下，用乙二醇对铜盐（Cu（NO ₃）₂）进行化学还原，而该石墨烯是由藻酸在Ar流下于900°C的热解获得的。使用该光催化剂，最大比CH ₄形成速率为14.93 mmol g _{Cu 2 O} ^-1 h ^-1表观量子产率为7.84％，在低于萨巴蒂尔反应温度（> 350°C）的温度下，是气相甲烷化反应的最高报道值。发现最可能的反应机理涉及光诱导电子从Cu ₂ O / G光催化剂向CO _2的转移，而证据表明光诱导的局部温度升高和H ₂活化可忽略不计。在该过程中温度的作用进行了研究，这表明加热可用数据需要以解吸ħ ₂形成为甲烷化过程中产品O操作。最可能的反应机理似乎遵循一种离解途径，其中涉及氧原子与一氧化碳的分离₂。