  We report protonation in several compounds by an ionic-liquid-gating method,
with optimized gating conditions. This leads to single superconducting phases
for several compounds. Non-volatility of protons allow post-gating
magnetization and transport measurements. The superconducting transition
temperature $T_C$ is enhanced to 43.5~K for FeSe$_{0.93}$S$_{0.07}$, and 41~K
for FeSe after protonation. Superconductivity with $T_c$$\approx$15~K for
ZrNCl, $\approx$7.2~K for 1$T$-TaS$_2$, and $\approx$3.8~K for Bi$_2$Se$_3$ are
induced after protonation. Electric transport in protonated
FeSe$_{0.93}$S$_{0.07}$ confirms high-temperature superconductivity. Our
$^{1}$H NMR measurements on protonated FeSe$_{1-x}$S$_{x}$ reveal enhanced
spin-lattice relaxation rate $1/^{1}T_1$ with increasing $x$, which is
consistent with LDA calculations that H$^{+}$ are located in the interstitial
sites close to the anions.
