There was a previous article posted on HN about a new record being set for speed of sound. The medium that transmitted the sound was high-pressure hydrogen. I

There was a previous article posted on HN about a new record being set for speed of sound. The medium that transmitted the sound was high-pressure hydrogen. I don't know what rabbit hole I stepped into, but it let me to an article about solid hydrogen acting as a metal and becoming an awesome super conductor at room temperature. I thought we had reached this record with solid hydrogen. But I cannot find this online anywhere. The material this article goes over is hydrogen-carbon-sulfide. The previous record for superconductivity was using hydrogen-sulfide. I wonder what other materials can be added to lower pressure at room temperature and maintain superconductivity. Lithium? Nickel? Copper?