No Woo Kwak

1 Introduction Ironmaking history essentially unfolds how we thermodynamically compete with O for extracting Fe from its feedstock, (hematite), (magnetite) and , (wüstite, where denotes the degree of Fe deficiency). Carbon-carrying fossil reductants are still extensively used to date in the iron and steel industry, rendering it a high footprint contributor with approximately 8 % of global annual carbon emissions in the past few years [1-3].

Synthesis of metal nanoparticles Figure 1 describes the overall synthesis processes to obtain metal nanoparticles (NPs) on an oxide support surface. It consists of two main steps. The first step is to feed metal sources into the grain boundaries of a host oxide. Here, we deposited metals on a sample surface by sputtering and then annealed the sample at 700 °C in air for the metals to diffuse into the host oxide.