Electrodissolution‐Coupled Hafnium Alkoxide Synthesis with High Environmental and Economic Benefits

Abstract

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.

Green Electrorefining of Crude Lead with High-Quality Deposits in an Additive-Assisted Methanesulfonic Acid System

“…Investigations on the replenishment mechanism of the electrolyte and additives as well as economic estimations of the cost input and output return for crude Pb electrorefining in the Lugalvan BNO12-assisted MSA system are now being performed. The energetic performance and process design of electrorefining would be further improved by low-investment microkinetic modeling. − Preparation of novel electrodes with nano- and polymeric materials will further improve the electrochemical performance of the deposition process. − The continuous drop in price of renewable electricity would further advance electrorefining toward lower-cost operation. Overall, crude Pb electrorefining in the Lugalvan BNO12-assisted MSA system would operate in a more technically and economically beneficial mode once receiving reasonable optimizations of process and condition and hold great potential toward practical application.…”

High-performance potassium poly(heptazine imide) films for photoelectrochemical water splitting

“…The migration of photogenerated charge carriers, namely electrons and holes, is of particular importance for photoelectrodes since the electrons or holes must travel through the entirety of photocatalytic films to the surfaces to participate in redox reactions. 38–40 In addition, the photocatalytic films are preferable to be anchored on a substrate via chemical bonding, allowing the photogenerated charge carriers to transfer from the working electrode to the counter electrode for redox reactions. 41,42 In situ approaches have been widely studied for inorganic semiconducting materials to allow efficient transfer of the photoexcitation charges.…”