Natural semiconducting minerals are widely distributed in supergene environments and are famous for their solar-driven redox activities, in which wolframite (Fe_xMn_1-xWO₄) as a fascinating member got less attention. In this work, the semiconducting photocatalytic activities of Fe_xMn_1-xWO₄ series samples (x = 1, 0.74, 0.48, 0.24, 0) influenced by their crystal chemistry were investigated. The bandgaps of MnWO₄, Fe_0.24Mn_0.76WO₄, Fe_0.48Mn_0.52WO₄, Fe_0.74Mn_0.26WO₄ and FeWO₄ as measured by UV–vis diffuse reflection (DRS), were 2.7, 2.4, 2.3, 2.2, and 2 eV, respectively, which were linearly decreased (R² = 0.971) when x increased from 0 to 1. The density functional theory (DFT) calculations further indicated with the increasing content of Fe, the contribution of valence-band maximum (VBM) was stepwise occupied by Fe 3d orbits and the bandgap was thus gradually decreased. The photocatalytic activities of Fe_xMn_1-xWO₄ samples were examined on the degradation of methylene blue (MB, 5 mg/L). The MB removal rate was the highest in Fe_0.74Mn_0.26WO₄ system, which was 3.2, 1.9, 1.2, and 1.5 times faster than that of MnWO₄, Fe_0.24Mn_0.76WO₄, Fe_0.48Mn_0.52WO₄, and FeWO₄, respectively. The concentration of produced hydroxyl radical (•OH) by Fe_xMn_1-xWO₄, detected in electron paramagnetic resonance (EPR) measurement, had a positive correlation with the degradation rate of MB. The degradation rate slowed down when •OH was removed, demonstrating that •OH was the major reactive oxygen species in the photocatalytic oxidative degradation of MB. The best-performing Fe_0.74Mn_0.26WO₄ photocatalytically produced the most •OH, which was closely linked with its most abundant oxygen-vacancy defects, revealed by X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. It thus can be concluded that narrow bandgap and appropriate oxygen vacancies can give rise to synergistic effect on the improvement of photocatalytic performance. This study helps get insight into the role of crystal chemistry in semiconducting properties and photocatalytic activities of wolframite, which also puts forward a new strategy to control environmental pollution by using natural minerals.

天然半导体矿物广泛分布于表生环境中，并以其太阳能驱动的氧化还原活性而闻名，其中引人入胜的黑钨矿（Fe _x Mn _1-x WO ₄）受到的关注较少。在这项工作中，研究了Fe _x Mn _1-x WO ₄系列样品（x = 1、0.74、0.48、0.24、0）受晶体化学性质的影响的半导体光催化活性。MnWO ₄，Fe _0.24 Mn _0.76 WO ₄，Fe _0.48 Mn _0.52 WO ₄，Fe _0.74 Mn _0.26的带隙通过UV-vis漫反射（DRS）测量的WO ₄和FeWO _4分别为2.7、2.4、2.3、2.2和2 eV， 当x从0增加到1时线性下降（R ² = 0.971）。密度泛函理论（DFT）的计算进一步表明，随着Fe含量的增加，Fe 3d轨道逐步占据了价带最大值（VBM）的贡献，带隙逐渐减小。研究了Fe _x Mn _1-x WO ₄样品对亚甲基蓝（MB，5 mg / L）降解的光催化活性。Fe _0.74 Mn _0.26 WO _4中的MB去除率最高系统，该系统是3.2，1.9，1.2和1.5倍比MnWO快₄，铁_0.24锰_0.76 WO ₄，铁_0.48锰_0.52 WO ₄，和FEWO ₄分别。在电子顺磁共振（EPR）测量中检测到的Fe _x Mn _1-x WO ₄产生的羟基自由基（•OH）的浓度与MB的降解速率呈正相关。当去除•OH时，降解速率减慢，表明•OH是MB的光催化氧化降解中的主要活性氧。表现最佳的铁_0.74锰X射线光电子能谱（XPS）和光致发光（PL）光谱表明，_0.26 WO ₄光催化产生最多的•OH，这与其最丰富的氧空位缺陷密切相关。因此可以得出结论，窄的带隙和适当的氧空位可以对光催化性能的改善产生协同作用。这项研究有助于深入了解晶体化学在黑钨矿的半导体性质和光催化活性中的作用，从而提出了一种利用天然矿物控制环境污染的新策略。