NOVELTY - Preparing substrate involves providing substrate including several nanopores extending from external surface; exposing substrate to first precursor within atomic layer deposition (ALD) system (10) for first predetermined period, the first precursor reacting with first surface portion of nanopores and depositing mask on first surface portion; exposing the substrate to second precursor within ALD system for second predetermined period, the second precursor reacting with second surface portion of nanopores, where mask prevents reaction of second precursor with first surface portion.    USE - For fabrication of catalysts, sensors, separations membranes, electron multipliers, solar cells, and nuclear fuel assemblies.    ADVANTAGE - The method forms multi-stripe, multi-material catalysts that precisely control reactions. Application of the masking precursor prevents adsorption of subsequently applied metal precursors a portion of the pore surface coated by the masking precursor. The depth of the metal stripe is controllable by regulating exposure of the porous substrate to the metal precursor.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) system for multi-step sequential reaction of a reactant comprising a substrate including nanopores extending between first and second substrate surfaces, each of the nanopores comprising an entrance proximate the first substrate surface; an exit proximate the second substrate surface; and a nanopore surface disposed between the entrance and the exit, at least a portion of the nanopores includes a first reactive region disposed on a first portion of the nanopore surface, and further includes a second reactive region disposed on a second portion of the nanopore surface, thus providing a sequential first and second reaction for a reactant that traverses from the entrance to the exit, where at least one of the first and the second portions is disposed at a distance from the entrance and the exit; and    (2) method for surface deposition of a material within a nanopore involving providing substrate having nanopores; providing a masking compound configured to coat at least a first portion of the internal surface of nanopores; and providing a first deposition compound configured to coat at least a second portion of the internal surface of the nanopores, the first deposition compound substantially nonreactive toward the masking compound, where the second portion of the internal surface is disposed at distance from the entrance.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of nanopore.    Atomic layer deposition system (10)    Nanopores (20)    Masking stripe (200)    Pore wall (250)    Pore entrance (260)