Sunlight drives photosynthesis and associated biological processes, and also influences inorganic processes that shape Earth’s climate and geochemistry. Bacterial solar-to-chemical energy conversion on this planet evolved to use an intricate intracellular process of phototrophy. However, a natural nonbiological counterpart to phototrophy has yet to be recognized. In this work, we reveal the inherent “phototrophic-like” behavior of vast expanses of natural rock/soil surfaces from deserts, red soils, and karst environments, all of which can drive photon-to-electron conversions. Using scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy, and X-ray absorption spectroscopy, Fe and Mn (oxyhydr)oxide-rich coatings were found in rock varnishes, as were Fe (oxyhydr)oxides on red soil surfaces and minute amounts of Mn oxides on karst rock surfaces. By directly fabricating a photoelectric detection device on the thin section of a rock varnish sample, we have recorded an in situ photocurrent micromapping of the coatings, which behave as highly sensitive and stable photoelectric systems. Additional measurements of red soil and powder separated from the outermost surface of karst rocks yielded photocurrents that are also sensitive to irradiation. The prominent solar-responsive capability of the phototrophic-like rocks/soils is ascribed to the semiconducting Fe- and Mn (oxyhydr)oxide-mineral coatings. The native semiconducting Fe/Mn-rich coatings may play a role similar, in part, to photosynthetic systems and thus provide a distinctive driving force for redox (bio)geochemistry on Earth’s surfaces.

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Phase pure perovskite 0.8Pb(Mg 1/3 Nb 2/3 )O 3 -0.2PbTiO 3 (0.8PMN-0.2PT) ferroelectric (FE) ceramics were prepared by the reaction-sintering method at a sintering temperature range of 1200-1250 8C. The sintered ceramics exhibit large relative density, where the 0.8PMN-0.2PT ceramics sintered at 1250 8C possess the largest value of relative density, reaching 99.56% of the theoretical density. All the sintered 0.8PMN-0.2PT ceramics exhibit broad, diffused, and frequency-dependent dielectric response peaks at around 80 8C and saturated and symmetric P-E hysteresis loops. The 0.8PMN-0.2PT ceramics exhibit excellent electrical properties, where the value of dielectric constant maximum e m is 35 750 at 1 kHz, the remanent polarization P r is 33.01 mC/cm 2 , the coercive field E c is 2.79 kV/ cm, and the piezoelectric constant d 33 is 259 pC/N.