Pulse-Driven Paired Electrosynthesis of Formamide via Redox-Tuned Intermediate Management

Abstract

Renewable electricity-driven electrocatalytic systems hold promise for the sustainable formamide (HCONH₂) synthesis. However, a major bottleneck remains the low Faradaic efficiency (FE) and overall electron utilization inherent to current unipolar C–N coupling strategies, where substantial electron consumption at the counter electrode severely limits system efficiency. Here, we propose a redox-tuned paradigm (A_red+ B_oxi→ C) through a pulsed paired electrosynthesis strategy. Using an atomically ordered CuPd catalyst with CH₃OH and NO₂^– as feedstocks in an undivided cell, HCONH₂ is simultaneously produced at both electrodes under optimized pulse conditions with alternating change in potential periodically (E_a = 1.3 V, t_a = 10 s; E_c = −0.7 V, t_c = 10 s). This system achieves an FE of 85.6% for HCONH₂ at a current density of 81.5 mA cm^–2, with a yield of 263.3 μmol·h^–1·cm^–2. The FE is higher than those reported to date. Mechanism studies reveal that pulsed operation creates a periodically switching cathode/anode environment. This enables the ordered CuPd catalyst to function sequentially as a reduction site (converting NO₂^– to *NH₃) during cathodic pulses and as a co-oxidation site (converting *NH₃ to *NH₂ along with CH₃OH to *HCOH) during anodic pulses, thereby driving efficient C–N bond coupling to form HCONH₂. Techno-economic analysis further confirmed the significant industrial potential of this strategy in the future renewable energy market.