Schottky Junction Effect on High Performance Fuel Cells Based on Nanocomposite Materials

Abstract

BHJ) structure. [ 9 ] The BHJ requires delicate tailoring of n-and p-particles in order to avoid the electronic short-circuit problem and make fuel cell function properly. [ 9 ] Hereby, we introduce the different Schottky junction type FC confi guration by means of combined nano and composite approach that is even simpler and more effective than EFFC.In a Schottky junction (SJ) FC device, a potential can be built up simply at the interface between a metal and an n-or p-type semiconductor, which is also termed as the Schottky barrier. [ 10 ] Based on this principle and making use of the depletion layer formed between the metal and the semiconductor, different types of Schottky junction devices have been demonstrated, such as solar cells and sensors. [11][12][13][14][15][16] One well-known function of SJ is to separate electrons/holes pairs by building up internal device voltage. Moreover, it has been reported that a Schottky junction formed between mesoporous n-TiO 2 semiconductor thin fi lm and a thin metal layer (such as Pt, Cu, Co, etc.) at anode/catalysts can effectively enhance the decomposition of aqueous biomass fuel solutions in combination with an O 2 -reducing cathode in a direct biomass fuel cell. [ 17,18 ] In this paper, we show that a SJ can be applied to ceramic FCs by using a composite of ionic and semiconducting materials to combine both semiconducting and ionic transporting properties, resulting in Schottky junction FC devices.Electrochemical reactions converting fuels, e.g., hydrogen into electricity through a FC is, to a high degree, affected by the quality of the ion-conducting electrolyte, which separates the anode and cathode to avoid short-circuit, [19][20][21] and brings about complex three-component (anode/electrolyte/cathode) confi guration as well. [ 22 ] The principle of SJ FC, based on a metal-semiconductor confi guration, is illustrated in Figure 1 . Different from the conventional FC device, i.e., instead of utilizing the electrolyte separator, the built-in fi eld and the barrier of the SJ serves the function of blocking electrons or holes from crossing the metal/semiconductor interface to the opposite side, resulting in no short-circuit of the device. The metal/ p-type semiconductor junction is favored because the builtin fi eld is directed from the metal surface to the p-type material, which can facilitate the ion transportation of H + (or O 2− ) crossing the metal/semiconductor-ionic material interface through ionic conductor at the same time, as shown in Figure 1 with corresponding energy band diagram schemes.The SJ FC was constructed from a hybrid oxygen-protonconducting material Ce 0.8 Sm 0.2 O 1.9 -Na 2 CO 3 (NSDC) [ 23 ] and p-type semiconducting materials Co-Li codoped NiO (LiNi 0.85 Co 0.15 O 2-δ , LCN for short), [ 24,25 ] in a weight ratio of 60:40 forming a composite (NSDC-LCN) ( Figure S1,The fi rst fuel cell (FC) invented by Grove in 1839 [ 1 ] was an electrochemical device by using a confi guration comprised of an anode, an electrolyte, and a cathode. Building on this...

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