The detrimental affect of fossil fuels on the worldwide local weather is driving the transition in the direction of carbon-neutral power applied sciences, resulting in growing curiosity in utilizing inexperienced hydrogen as an power service[1]. Strong oxide gas cells (SOFCs) and stable oxide electrolysis cells (SOECs), collectively denoted by the overarching time period SOCs, are a vital a part of the inexperienced hydrogen economic system[2], [3]. SOFCs effectively convert chemical power from hydrogen and different fuels into electrical energy at elevated operational temperatures sometimes ranging between 600 and 800°C, providing excessive effectivity and low emissions[4], [5]. Whereas SOECs make the most of renewable electrical energy to provide hydrogen via water electrolysis or carbon monoxide via direct CO2 electrolysis or synthesis fuel via co-electrolysis[1], [6]. These merchandise might be additional used as a sustainable uncooked supplies for the chemical trade reminiscent of Energy-to-X, Energy-to-Chemical compounds or Energy-to-Gasoline or Energy-to-Warmth and therefore facilitate the mixing of renewably generated energy on a big scale[7]. Thus, SOCs are more likely to play essential function not solely in decarbonization but additionally within the defossilization of the power sector.
The three main elements of SOCs encompass the dense electrolyte, characterised by excessive ionic conductivity, and the porous electrodes, particularly the anode and cathode, which exhibit each ionic and digital conductivity[4]. The gas electrode, often known as the anode in SOFC mode or the cathode in SOEC mode, is among the most vital elements of SOCs due to its direct contact with various kinds of gas. Albeit the Ni-yttria-stabilized zirconia (Ni-YSZ) cermet is essentially the most broadly used gas electrode materials in SOCs owing to its comparatively decrease prices, excessive mechanical energy, and appropriate thermal growth coefficient with YSZ electrolyte, it isn’t with out its limitations[8], [9], [10]. A number of drawbacks accompany the Ni-YSZ cermet, together with poor redox stability, nickel agglomeration, nickel deactivation attributable to coking, and susceptibility to sulfur poisoning, amongst others[9], [10], [11], [12], [13]. In its place method, varied perovskite and double-perovskite supplies have been extensively investigated for SOC purposes in the previous couple of years, reminiscent of Sr2MnMoO6-δ [8], La0.75Sr0.25Cr0.5Mn0.5O3 [14], SrTiO3 [15], Sr2Fe1.5Mo0.5O6-δ [16]. Amongst such supplies, Sr2FeMoO6-δ (SFM), with the double-perovskite A2BB′O6 construction, has garnered important consideration as a result of its promising efficiency attributes, notably its distinctive electrochemical stability, symmetrical performance, and blended electronic-ionic conductivity (MIEC)[16], [17], [18], [19], [20], [21]. The MIEC properties in SFM are because of the presence of quite a few oxygen emptiness websites throughout the guardian lattice[3], [16], [17]. Completely different research have focussed on doping B/B′ cationic websites of SFM with transition metals reminiscent of Ni, Co, Mn, and others to reinforce their efficiency[19], [20], [21]. In such doped perovskites, there may be an in situ exsolution of the B/B′-site cations upon discount[21], [22]. Such metallic exsolutions improve the general cell efficiency when used as electrodes in SOCs as a result of a rise within the efficient floor space accessible for catalytic exercise[22], [23], [24]. It has additionally been noticed, that there’s an anchoring impact between such metallic exsolutions and the guardian materials which impedes the grain coarsening, reduces hydrocarbon coking, and mitigates the agglomeration of the exsolutions[20], [21], [22], [23]. Among the many totally different doped variants of SFM, nickel-doped SFM has constantly exhibited essentially the most promising efficiency traits in quite a few research[19], [20], [21], [22], [23], [24], [25]. However, such ex situ research fail to elucidate the mechanisms concerned within the strategy of in situ exsolution course of and the conduct of the exsolved particles underneath response. These visualizations are important for higher design of supplies and thereby for enhancing electrochemical efficiency on the macro stage.
Transmission electron microscope (TEM) provides the chance to analyze the structural, morphological, and chemical info as much as atomic scale. And, due to the current developments of specialised pattern holders, TEM has turn out to be a super choice for visualization of dynamic processes on the nanoscale[26], [27], [28]. Nevertheless, the nano-to-macro scale distinction must be saved in thoughts earlier than generalizing the nano-scale in situ TEM outcomes to foretell the machine efficiency on the macro scale. This searched for a multi-modal method[29]. Thus, on this research to grasp the underlying mechanisms of exsolution of Sr2FeMo0.65Ni0.35O6-δ particles, first exsolution course of was visualized at totally different temperatures and pressures via in situ (E)TEM. Subsequent, to look at the conduct of the exsolved particles throughout the catalytic response the Sr2FeMo0.65Ni0.35O6-δ particles with exsolved bimetallic particles had been subjected to CO2 and H2 at totally different ratios. To evaluate the general affect of those exsolutions on electrochemical efficiency and for nano-to-macro correlation, symmetrical button cells of SFM-Ni had been constructed and subjected to typical electrochemical processes, coupled with electrochemical, spectroscopic, and 3D microscopic investigation with FIB-SEM tomography.
