NOVELTY - Method (M1) for storing and releasing a gas responsive to the application of an electric field, involves: (A) providing a piezoelectric metal-organic framework material (110), where the piezoelectric metal-organic framework material is configured to adsorb at least a portion of the gas in response to the application of an electric field; (B) adsorbing at least a portion of the gas into the piezoelectric metal-organic framework material; and (C) applying an electric field to the piezoelectric metal-organic framework material to release a portion of the gas.    USE - For storing and releasing gas, where gas is hydrogen, carbon dioxide, ammonia, boron trifluoride, and/or aluminum trifluoride (claimed), for gas storage and release in variety of applications, such as fuel cells or fuel delivery applications in wide variety of implementations such as automobiles, hand held devices (such as cell phones, gaming devices or personal digital assistants), laptop computers or industrial applications; materials, chemicals or semiconductor processing; micro-electro-mechanical systems, pneumatics systems, motion devices, and measurement devices. Also useful for gas purification and separation.    ADVANTAGE - The method for storing and releasing gas responsive to application of electric field, is useful in applications where it is necessary to release gases quickly, and accurately or at high pressure; where current methods for storing and releasing gases may be difficult, energy intensive, or uneconomical for some applications. In the method, piezoelectric metal-organic framework material is provided for storage and release of gas, where piezoelectric metal-organic framework material is non-centrosymmetric metal-organic framework. The piezoelectric metal-organic framework material readily adsorbs gas with no applied electric field, such that material may be adsorptive in its relaxed state, applied electric field releases adsorbed gas, and release of stored gas is responsive to magnitude of applied electric fields such that electric field with greater magnitude causes more gas to be released; or piezoelectric metal-organic framework material adsorbs gas with applied electric field and releases gas when electric field is removed or field strength is lowered. The electric field changes shape, size or geometry of piezoelectric metal-organic framework material such that material may store or release gas. The piezoelectric metal-organic framework material responds to applied electric field with net stress throughout material that may at least partially change its size, shape or geometry such that at different electric field strengths, the material has different gas sorption characteristics. The piezoelectric metal-organic framework material can be constructed from diverse set of building blocks, such that final material may be constructed to include various functionalities and characteristics e.g. gas sorption, gas selectivity, piezoelectric properties, density properties, or weight properties. Thus, such systems may allow for accurate modulation of applied pressure, or amount of released gas based at least in part on variation in electric field strength, which may be controlled to precise degree. Based at least in part on geometry of metal-organic framework, large amount of adsorptive surface area may be provided in relatively small volume, such that piezoelectric metal-organic framework material has porous structure that provides gas storage capacity in relatively small volume. The piezoelectric metal-organic framework material provides gas storage at relative low pressures, and at room temperature and/or pressure. As piezoelectric metal-organic framework material selectively adsorbs gas based at least in part on magnitude of applied electric field, one type of gas is adsorbed at one field strength, and another type of gas is adsorbed at other field strength. The method and apparatus are also useful for gas purification and separation. The piezoelectric metal-organic framework materials selectively remove gas (or gases) from mixture such that separation or purification can be achieved, and gas removed from mixture into piezoelectric metal-organic framework material can be subsequently released.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method (M1a) for storing and releasing a gas involving: (a1) providing a piezoelectric metal-organic framework material; (b1) applying an electric field to the piezoelectric metal-organic framework material; (c1) adsorbing at least a portion of the gas into the metal-organic framework material during application of the electric field; and (d1) reducing an electric field strength of the electric field to release at least a portion of the gas; and    (2) an apparatus (100) that is arranged to store a gas and release the gas responsive to the application of an electric field, comprising: a piezoelectric metal-organic framework material configured to adsorb at least a portion of the gas in response to the application of an electric field.    DESCRIPTION OF DRAWING(S) - The figure shows the device for storing and releasing gas.    Gas storage and release device/apparatus (100)    Piezoelectric metal-organic framework material (110)    Electrodes (120, 125)    Connectors (130, 135)