湖南大学邹雨芹团队在研究中取得进展。他们提出了通过调节分子吸附选择性的断裂苯氧键，实现水基中电催化加氢解聚木质素β-O-4键。相关论文于2024年11月5日发表在《美国化学会杂志》上。

课题组研究人员报道了一种通过调节分子吸附，来破坏苯氧键的水性电化学还原策略。密度泛函理论（DFT）计算和石英晶体微天平（QCM）测量结果表明，CuO电催化剂中残留的Cu(I)增强了苯氧键对2-苯氧基-1-苯乙醇（PPE）的吸附，降低了β-O-4键中攻击氧原子的质子的能垒。与Cu电催化剂（对苯二酚收率为47.4%，苯甲醇收率为24.8%）相比，CuO纳米棒在-0.4 V的可逆氢电极（RHE）电位下，在未分裂电池中具有更高的对苯二酚收率（95.3%）和苯甲醇收率（88.6%）。

此外，通过原位同步辐射红外光谱（SR-FTIR）和DFT计算相结合，确定了反应途径和苯氧键的裂解。该方法可用于木质素电解，愈创木酰甘油得率为10.9%，选择性为＞63.0%。本研究为木质素活化过程中苯氧键的裂解提供了一种高效、温和的方法。

据了解，木质素β-O-4键的苯氧键的断裂有望缓解降解产物的缩合，提高产物的价值。然而，由于苯氧键的高解离能（~409 kJ mol-1）和芳香族化合物容易过还原，尚未实现苯氧键的电化学断裂。

附：英文原文

Title: Aqueous Electrocatalytic Hydrogenation Depolymerization of Lignin β-O-4 Linkage via Selective Caryl–O(C) Bond Cleavage: The Regulation of Adsorption

Author: Yuanqing He, Xu Zeng, Zhuoran Lu, Shiheng Mo, Qizheng An, Qinghua Liu, Yulu Yang, Wu Lan, Shuangyin Wang, Yuqin Zou

Issue&Volume: November 5, 2024

Abstract: The cleavage of the benzene–oxygen (Caryl–O(C)) bond of the lignin β-O-4 linkage is expected to relieve condensation of the degradation product and improve the product value. Nevertheless, the electrochemical breaking of the Caryl–O(C) bond has not been achieved yet due to the high dissociation energy (～409 kJ mol–1) and the easy over-reduction of aromatic compounds. Here, we report an aqueous electrochemical reduction strategy for breaking Caryl–O(C) bonds via the regulation of molecular adsorption. The density functional theory (DFT) calculations and quartz crystal microbalance (QCM) measurements reveal that the residual Cu(I) in the CuO electrocatalyst enhances the adsorption of the 2-phenoxy-1-phenylethyl alcohol (PPE) by the Caryl–O(C) bond and lowers the energy barrier of the protons attacking the oxygen atom in the β-O-4 linkage. Thus, compared to the Cu electrocatalyst (with a hydroquinone yield of 47.4% and a benzyl alcohol yield of 24.8%), the CuO nanorod exhibits a much higher yield of hydroquinone (95.3%) and benzyl alcohol (88.6%) at a potential of 0.4 V vs reversible hydrogen electrode (RHE) in an undivided cell. Moreover, the reaction pathway and the cleavage of the Caryl–O(C) bond are identified through a combination of in situ synchrotron-radiation Fourier transformed infrared spectroscopy (SR-FTIR) and DFT calculations. This effective method is utilized for poplar lignin electrolysis, yielding 10.9 wt % of guaiacylglycerol, with an outstanding selectivity of >63.0%. This work provides an efficient and mild method of cleavage of Caryl–O(C) bonds in lignin valorization.

DOI: 10.1021/jacs.4c12220

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c12220