The conventional thermal method of preparing hafnium alkoxides [Hf(OR) 4 , R = alkyl] -excellent precursors for gatedielectric HfO 2 on semiconductors -is severely hindered by its unsatisfactory environmental and economic burdens. Herein, we propose a promising electrodissolution-coupled Hf(OR) 4 synthesis (EHS) system for green and efficient electrosynthesis of Hf(OR) 4 . The operational principle of the electrically driven system consists of two simultaneous heterogeneous reactions of Hf dissolution and alcohol dehydrogenation, plus a spontaneous solution-based combination reaction. In applying ethanol as solvent and Hf metal as electrodissolution medium, we achieved waste-free production of high-purity hafnium ethoxide [Hf(OEt) 4 ] with an equivalent "a concomitant" reduction in CO 2 emission of 187.33 g CO 2 per kg Hf(OEt) 4 and a high net profit of 30 477 USD per kg Hf(OEt) 4 . This system is very competitive with the thermal process, which unavoidably releases substantial waste and CO 2 for a net profit of 27 700 USD per kg Hf(OEt) 4 . We anticipate that the environmental and economic benefits of the EHS process could pave the way for its practical application.

The electrodissolution-coupled hafnium alkoxide (Hf(OR)4, R is alkyl) synthesis (EHS) system, which has significant environmental and economic advantages over conventional thermal methods, serves as a promising system for green and efficient Hf(OR)4 electro-synthesis. The EHS system is operated based on the simultaneous heterogeneous reactions of hafnium dissolution and ethanol dehydrogenation, as well as the spontaneous solution-based reaction of Hf4+ and OR−. Employing green ethanol and Hf as feedstocks, the anodic hafnium corrosion/dissolution electrochemical behavior of the Et4NCl or Et4NHSO4 based anhydrous system was investigated through electrochemical measurements combined with SEM observations. The results demonstrated that the Et4NCl-based anhydrous ethanol system exhibited an efficient mechanism of passive film pitting corrosion breakdown and metal hafnium dissolution, while the Et4NHSO4-based anhydrous ethanol system reflected the weak corrosion mechanism of the anodic hafnium under the passive film. The polarization resistance of the Et4NCl system was dramatically lower than that of the Et4NHSO4 system, which indicated that the Et4NCl system had superior anodic hafnium corrosion performance compared to the Et4NHSO4 system. Overall, the investigation of the electrochemical behaviors of anodic hafnium corrosion/dissolution provides theoretical guidance for the efficient operation of EHS electrolysis.

The Cover Feature shows a novel system that simultaneously prepares high‐value hafnium alkoxide (a robust precursor of semiconductors) and “negative carbon” hydrogen. Being able to couple with a renewable source, this electrically driven system consists of two simultaneous heterogeneous reactions of Hf dissolution and alcohol dehydrogenation and a spontaneous solution‐based combination reaction. We demonstrate the green advances of the electrified system on sustainability and economy over previous thermally driven systems, which shows its great potential towards practical application. More information can be found in the Research Article by S. Li et al.

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