In one aspect, an apparatus includes a diffusive memristor, and a capacitor integrated in series with the diffusive memristor, wherein the apparatus exhibits volatile memcapacitive behavior. In another aspect, a device includes a transistor, and a memcapacitor integrated onto the gate of the transistor, wherein the memcapacitor exhibits volatile memcapacitive behavior. The memcapacitor includes a diffusive memristor, and a capacitor integrated in series with the diffusive memristor, wherein the gate dielectric of the transistor is replaced with the memcapacitor. In another aspect, an artificial neuron device includes a transistor, a volatile memcapacitor that is configured to operate as an electrically floating gate of the transistor, and one or more synaptic circuits that are coupled to the volatile memcapacitor. The volatile memcapacitor includes a diffusive memristor, and a capacitor integrated in series with the diffusive memristor.