The anodic behaviors of bare nickel, nickel-based composite, and carbon electrodes in molten fluorides containing HF such as NH
4F·2HF and NH
4F·KF·
mHF (
m=3 and 4) at 100°C are described from the viewpoints of NF
3 formation, the oxidized layer formation, and the anodic dissolution. Although the anodic dissolution of the nickel based composite electrodes was smaller than that of the nickel electrode, the current efficiency for NF
3 formation decreased slightly on the nickel-oxide composite electrode, because of water formed through the reaction of the oxides with HF in the melt. Addition of LiF to the melt was effective for increasing the current efficiency for NF
3 formation and decreasing the anode consumption of the nickel and nickel-based composite electrodes. Fluorine-graphite intercalation compounds (GICs) having stage numbers higher than three were detected on the surface of carbon electrode after pre-electrolysis at 2.3 V and then 4 V, and the presence of the GIC layer suppressed the occurrence of the anode effect during electrolysis for NF
3 production. Boron-doped Diamond (BDD) anodes were developed and their anode performance for electrochemical synthesis was investigated. The anode potential even at 1000 mA cm
−2 on a BDD electrode was much lower than those at 100 or 30 mA cm
−2 on a nickel and a pristine carbon FE-5 electrode and no anode effect took place up to 1000 mA cm
−2. That is, the electrolysis with the BDD anode can be conducted at a high current density for long duration. The current efficiency for NF
3 formation on the BDD anode was the highest among these anodes and its maximum value was 72.4%. Therefore, BDDs are promising candidates for anode materials in electrolytic production of NF
3.
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