Superprotonic CsH2PO4 in dry air

CsH2PO4 is not stable at 260 °C unless confined. Comments to article by C.E. Botez, I. Martinez, A. Price, H. Martinez, and J.H. Leal in J. Phys. Chem. Solids 129 (2019) 324-328

“…Comparison of our results with the results by Botez et al [1]. The recent results of Botez et al [1] are shown in Fig. 1, together with our own results [2] on similar scales.…”

“…We discuss in the following our own observations and high pressure atmosphere, eventually formed from the sample itself. The temperature-and time-resolved impedance spectroscopy data by Botez et al [1] have shown that a CDP pellet measured in a hermetically sealed chamber holds a stable protonic superconductivity of ∼2 × 10 −2 S cm −1 over a timespan of 50 h and at a temperature of 260 °C, but -as we calculate below -their amount of sample was large enough and their hermetically closed container was small enough to leave enough CDP to give the impression from Nyquist plots that the pellet was superconducting.…”

WITHDRAWN: Preparation, Characterization, and Stability of the (1-x) CsH2PO4 + xTiO2 Composite Electrolytes for Fuel Cells

“…If the CDP pellet is con ned hermetically in a tide and sealed container, the dehydration is greatly reduced. The proton conductivity slightly increased concerning temperature range between 235 to 260 o C [3,30]. We observed that the conductivity of CDP at a lower temperature is more than its composites, while at a higher temperature the conductivity of its composites is more than CDP.…”

“…CsH 2 PO 4 has proton conductivity 1.8×10 − 6 at a temperature of 150°C [10] and showed high conductivity 2.2× 10 − 2 S cm -1 at the temperature of 240°C [11]. Botez et al [3] reported 1.5×10 − 2 S cm -1 high conductivity of CDP at the temperature of 260°C. CDP achieved high proton conductivity of 2.0× 10 -2 S cm -1 up to 260°C for 50 hours under high atmospheric pressure and high humidity when the container is con ned in a small container [12].…”

“…CDP is considered as one of the highly conductive materials [3][4][5] in the family of acid salts M α H β (NO 4 ) γ (M = Li, Na, K, Rb, Cs, NH 4 ): N = P, S, As, Se, and α, β, γ, are integers for fuel cell electrolytes [6][7][8][9]. CsH 2 PO 4 has proton conductivity 1.8×10 − 6 at a temperature of 150°C [10] and showed high conductivity 2.2× 10 − 2 S cm -1 at the temperature of 240°C [11].…”