## 1 Introduction  
Ruthenium oxide (RuO\({}_{x}\)) is a promising-material both in the context of catalysis [1,2] and energy [3]. For instance, combinations and composites based on metallic ruthenium/ruthenium oxides are notable for coupling reaction catalysis [4], catalyzing the photochemical reduction of water [5], as thin film resistors for inkjet printing [6] and as catalysts for N\(\mathrm{\SIUnitSymbolO}\) decomposition [7], selective oxidation of alcohol [8] and oxidation of carbon monoxide (CO) [9, 10, 11]. Among the above chemical processes, CO oxidation is an attractive one for study since it is both an industrially important reaction and relatively uncomplicated to model experimentally and computationally. The impact of CO on environmental air quality is considerable and as a toxic gas an exposure of 800 ppm for 1 h is fatal to human life [12]. Noble metal catalysts such as Pt and Pd exhibit good CO oxidation activity but concerns over cost and abundance have compelled researchers to develop metal oxides as a viable alternative [13, 14, 15, 16]. The catalytic activity of candidate metal oxide systems is heavily dependent on oxidation state and for example in the Ru-O system, when a RuO\({}_{2}\) catalyst is used under a high partial pressure of O\({}_{2}\), it exhibits a superior CO oxidation performance than metallic Ru catalysts [10,17]. Moreover, the performance of such catalysts can be greatly improved when stabilized or uniformly dispersed on the surface of a suitable support [18, 19, 20].  
Dispersion is a critical step in furthering an effective reaction between the reactants [21]. Conventional methods of catalyst dispersion on support materials by wet impregnation often yield aggregated structures [22]. Polymers can be used in nanomaterial syntheses as stabilizers, surfactants or growth-directing agents [23,24] in which they control the particle aggregation, pore characteristics and in a catalysis context, the stability and poisoning resistance of the support [25]. Polyethylene glycol (PEG) is one of the most widely-used polymers in the design of heterogeneous catalysts [26] and can increase the interaction between the catalyst and the support by altering the physicochemical properties. Polymer additives need to be chosen carefully so as not to hinder the catalytic process and need to be removed by heat treatment prior to the experiment. Even though many surfactant materials are commercially available, PEG is an attractive choice as an additive since its oxidation products contain no nitrogen, sulfur or phosphorous thus precluding catalyst poisoning during heat treatment [27]. There are several reports describing the use of polymer stabilizers for the preparation of the catalysts [28, 29, 30], but very few detailed studies on the surfactant-induced morphological changes and subsequent correlations with activity are reported. A fuller understanding of such relationships provides a useful means to improve catalyst performance. In this study, the CO oxidation performance (both in wet and dry conditions) of a PEG-stabilized RuO\({}_{x}\)/-Al\({}_{2}\)O\({}_{3}\) catalyst is compared with an un-stabilized equivalent. Detailed physical and chemical characterization of the materials has allowed us to begin to understand the connectivity between surfactant-mediated RuO\({}_{x}\) catalyst design and activity.