NOVELTY - The membrane (222) comprises a graphene layer perforated by nanoscale pores (206), and a gas sorbent configured to contact a surface of the graphene layer between the nanoscale pores and to direct a gas adsorbed at the gas sorbent into the nanoscale pores. Each nanoscale pores is characterized by an average diameter of 0.1-4 nm. The pores have same size such that the graphene layer has uniform pore sizes throughout. Each nanoscale pore is characterized by carbon vacancy defects in the graphene monolayer (204) such that the graphene layer has uniform pore sizes throughout.    USE - The membrane is useful for separating a gas from a fluid mixture including a first gas and a second gas, where the first gas includes helium, neon, argon, xenon, krypton, radon, hydrogen, nitrogen, oxygen, carbon monoxide, carbon dioxide, sulfur dioxide, hydrogen sulfide, a nitrogen oxide, a 1-4C alkane, a silane, water or a haloacid (all claimed).    ADVANTAGE - The membrane has greater selectivity and gas permeation rates, and increased transport rates for gas molecules.    DETAILED DESCRIPTION - The membrane (222) comprises a graphene layer perforated by nanoscale pores (206), and a gas sorbent configured to contact a surface of the graphene layer between the nanoscale pores and to direct a gas adsorbed at the gas sorbent into the nanoscale pores. Each nanoscale pores is characterized by an average diameter of 0.1-4 nm. The pores have same size such that the graphene layer has uniform pore sizes throughout. Each nanoscale pore is characterized by carbon vacancy defects in the graphene monolayer (204) such that the graphene layer has uniform pore sizes throughout. The gas sorbent comprises nanoparticles having a diameter of 20-100 nm, and an atomic monolayer. The gas sorbent at a surface of the graphene layer has a thickness of 1 atom to 1 micron. A portion of the nanoscale pores is free from obstruction by the gas sorbent layer, and is partly occluded by the gas sorbent. INDEPENDENT CLAIMS are included for:    (1) a method of forming a membrane; and    (2) a method of separating a gas from a fluid mixture.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a membrane.    Graphene monolayer (204)    Pores (206)    Membrane's top view (220)    Membrane (222)    Gas sorbent particles. (228)