Tuning interlayer spacing of graphene oxide membrane to enhance its separation performance of hydrogen isotopic water in membrane distillation

•Interlayer spacing of GO membranes was tuned by intercalation and cross-linking ways.•Intercalated GO-Ca2+ membranes showed higher permeation flux than GO membranes.•Cross-linked GO-Al3+ membranes exhibited enhanced overall separation performance.•Tuning interlayer spacing and structure of GO membranes favoured H2O/D2O separation.•Selectivity-permeability of H2O/D2O separation in membrane distillation was studied.