It is highly desirable to design efficient and stable hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) electrocatalysts for the development of renewable energy technologies. Herein, density functional theory (DFT) calculations were conducted to systematically investigate a series of TMN_xO_4−x-HTT (TM = Fe, Co, Ni, Ru, Rh, Pd, Ir and Pt; HTT = hexahydroxy tetraazanaphthotetraphene) analogs of two-dimensional (2D) conductive metal-organic frameworks (MOFs) as potential electrocatalysts for the HER, OER and ORR. The thermodynamic and electrochemical stability simulations suggest that these designed catalysts are stable. Remarkably, CoO₄-HTT, RhN₃O₁-HTT and IrN₃O₁-HTT are predicted to be the most promising catalysts for the HER, OER and ORR, respectively, surpassing the catalytic activity of corresponding benchmark catalysts. The volcano plots were established based on the scaling relationship of adsorption Gibbs free energy of intermediates. The results reveal that regulating combinations of metal active centers and local coordination environments could effectively balance the interaction strength between intermediates and catalysts, thus achieving optimal catalytic activity. Our findings not only opt for the promising HER/OER/ORR electrocatalysts but also guide the design of efficient electrocatalysts based on 2D MOFs materials.

The high performance of two-dimensional (2D) channel membranes is generally achieved by preparing ultrathin or forming short channels with less tortuous transport through self-assembly of small flakes, demonstrating potential for highly efficient water desalination and purification, gas and ion separation, and organic solvent waste treatment. Here, we report the construction of vertical channels in graphene oxide (GO) membrane based on a substrate template with asymmetric pores. The membranes achieved water permeance of 2647 L m⁻² h⁻¹ bar⁻¹ while still maintaining an ultrahigh rejection rate of 99.9% for heavy metal ions, which is superior to the state-of-the-art 2D membranes reported. Furthermore, the membranes exhibited excellent stability during long-term filtration experiments for at least 48 h, as well as resistance to ultrasonic treatment for over 100 minutes. The vertical channels possess very short pathway for almost direct water transport and a highly effective channel area, meanwhile the asymmetric porous template enhances the packing of the inserted GO nanosheets to avoid the swelling effect of membrane. Our work provides a simple way to fabricate vertical channels of 2D nanofiltration membranes with high water purification performance.

RhO₄-HTC and RhN₂O₂-HTC based on 2D conductive MOFs are screened out as potential OER and ORR bifunctional electrocatalysts by using DFT calculations.