# Superconducting single-layer T-graphene and novel synthesis routes

## TL;DR

This paper predicts a new single-layer superconducting material called T-graphene with a Tc of around 20.8 K, proposes a synthesis method involving high-pressure intercalation, and reports a record Tc of 30.4 K for related compounds.

## Contribution

It introduces a novel 2D carbon superconductor T-graphene, predicts its properties, and proposes a feasible synthesis route, advancing the field of elemental 2D superconductors.

## Key findings

- T-graphene is predicted to be an intrinsic superconductor with Tc ~20.8 K.
- A synthesis route involving high-pressure intercalation and exfoliation is proposed.
- The Tc of C4K is calculated to be about 30.4 K, setting a new record for layered carbon superconductors.

## Abstract

Single-layer superconductors are ideal materials for fabricating superconducting nano devices. However, up to date, very few single-layer elemental superconductors have been predicted and especially no one has been successfully synthesized yet. Here, using crystal structure search techniques and ab initio calculations, we predict that a single-layer planar carbon sheet with 4- and 8-membered rings called T-graphene is a new intrinsic elemental superconductor with superconducting critical temperature (Tc) up to around 20.8 K. More importantly, we propose a synthesis route to obtain such a single-layer T-graphene, that is, a T-graphene potassium intercalation compound (C4K with P4/mmm symmetry) is firstly synthesized at high pressure (>11.5GPa) and then quenched to ambient condition; and finally, the single-layer T-graphene can be either exfoliated using the electrochemical method from the bulk C4K, or peeled off from bulk T-graphite C4, where C4 can be obtained from C4K by evaporating the K atoms. Interestingly, we find that the calculated Tc of C4K is about 30.4K at 0GPa, which sets a new record for layered carbon-based superconductors. The present findings add a new class of carbon based superconductors. In particular, once the single-layer T-graphene is synthesized, it can pave the way for fabricating superconducting devices together with other 2D materials using the layer-by-layer growth techniques.